# I'm doing math again and my head hurts **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [August 8, 2009, 10:13pm UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779 "2009-08-08T22:13:07Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Jamaika\_a\_jamaikaiake](https://avatars.discourse-cdn.com/v4/letter/j/7993a0/32.png) [@Jamaika\_a\_jamaikaiake](https://boards.straightdope.com/u/Jamaika_a_jamaikaiake)\ **Post date:** [August 10, 2009, 2:52am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/41 "2009-08-10T02:52:50Z")
> [@Dr.Love](#): > > I’ve read this before, and I think that Lockhart really goes off the deep end with his belief that mathematics ought to be useless. Near as I can tell this opinion is less than a century old, and started with [G. H. Hardy](http://en.wikipedia.org/wiki/G._H._Hardy), who’s mathematical work has actually found a number of uses. > > I do try to think of physical reasons for the facts of math as much as I can. It’s crazy to say that math should be application-less when, say, the “negative time negative equals positive” rule exists because it makes calculations in the real world work. Sure, it doesn’t need to be useless (does he say that, really?), but it needn’t be useful either. In any case, most of K-12 math _is_ useless for most people. ---
**Author:** ![Dr.Love](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@Dr.Love](https://boards.straightdope.com/u/Dr.Love)\ **Post date:** [August 10, 2009, 3:46am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/42 "2009-08-10T03:46:07Z")
> [@Indistinguishable](#): > > I’d say it exists because it’s mathematically simplest… it preserves the distributive property of multiplication over addition, and such things. That this “makes calculations in the real world work” is a secondary consideration that simply follows from that. Any other system would be all the uglier and more ad hoc for destroying such a nice pattern, and thus have less natural applications or interest, real world or otherwise. I hadn’t noticed that before. Neat. Anyway, if any of the non-mathematicians in this thread need another reason to doubt Lockhart’s insistence on the beauty of uselessness, just look at the number of great mathematicians who applied their math to physics, astronomy or engineering: Newton, Gauss, Euler, Archimedes, Lagrange, Laplace, Hilbert, and many more. > [@Jamaika\_a\_jamaikaiake](#): > > Sure, it doesn’t need to be useless (does he say that, really?), but it needn’t be useful either. I don’t know that he says it outright (Hardy, who influenced him, does), but that’s always the impression I get when reading the essay. For example > [@Paul Lockhart](#): > > I wonder how much of the box the triangle takes up? Two-thirds maybe? The important thing to understand is that I’m not talking about this _drawing_ of a triangle in a box. Nor am I talking about some metal triangle forming part of a girder system for a bridge. There’s no ulterior practical purpose here. I’m just _playing_. That’s what math is— wondering, playing, amusing yourself with your imagination. [Original italics, pg 4] Yeah, sometimes you’re just playing with concepts that are only in your head. But, a number of important mathematical results have come from people wondering how gravity works. You wouldn’t suspect this if you just listened to Lockahrt. ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [August 10, 2009, 3:51am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/43 "2009-08-10T03:51:25Z")
> [@friedo](#): > > “Completing the square” is something that sounds vaguely familiar, but I must admit I have no idea what it means, and couldn’t follow any of the explanations upon a cursory Google search. It just means manipulating the equation until you have a perfect square on one side. An example (admittedly very easy, because you can factorise it at a glance anyway): x[sup]2[/sup]-2x-8=0 x[sup]2[/sup]-2x=8 x[sup]2[/sup]-2x+1=9 (x-1)[sup]2[/sup]=9 (x-1)=3 or -3 x=4 or -2 Once you’ve had to use this method lots of times on more complicated quadratics, you can derive the general formula by completing the square on ax[sup]2[/sup]+bx+c=0 at the drop of a hat. ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [August 10, 2009, 3:52am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/44 "2009-08-10T03:52:45Z")
Oops. I made a double post ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 10, 2009, 3:58am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/45 "2009-08-10T03:58:06Z")
> [@Cunctator](#): > > It just means manipulating the equation until you have a perfect square on one side. An example (admittedly very easy, because you can factorise it at a glance anyway): > > \ Basically, take half of the coefficient of x, square it, and add it to both sides. EDIT: After dividing my the coefficient of x[sup]2[/sup] of course. ---
**Author:** ![eleanorigby](https://avatars.discourse-cdn.com/v4/letter/e/ee7513/32.png) [@eleanorigby](https://boards.straightdope.com/u/eleanorigby)\ **Post date:** [August 10, 2009, 4:16am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/46 "2009-08-10T04:16:33Z")
Note: this is not really directed at Thudlow. These are feelings and experiences I have had with math. I envy those to whom math comes easily. I don’t think you all know how truly difficult it can be for others. > [@Thudlow\_Boink](#): > > But the thing is, math does make sense. Unlike other subjects, everything in math is stuff you could figure out for yourself, if you were clever enough and thought about it long and hard enough. No, this is not true. Everything in math does NOT make sense, unless you accept underlying premises (or principles). “Imagine a unit circle with a circumference of 1” was how my Trig class started. Since I can imagine circles (I had no idea why it was called a “unit” circle; I still don’t and I don’t care) of any circumference, I lost interest that first day. Not that I had a lot to begin with. Arithmetic, is very useful, as are some basic equations such as distance=rate x time, but other than that, it is not useful or logical to me. WTF is the quadratic equation FOR? I can stare at a word problem for hours and not know where to start in solving it–I may not even know WHAT they want me to solve for. I can figure out area and perimeter–and that’s about it. > [@](#): > > There’s nothing arbitrary: the way things work is the way they _have_ to work in order to be consistent with everything else. Well that’s not entirely true: there are some arbitrary things you just have to learn, especially in the realm of notation, like the symbols 1, 2, 3, 4, etc. But mostly, math is just what’s logical. Euclid’s _Elements_, the most famous math text of all time, starts with just a handful of assumptions and logically deduces a vast amount of mathematics from them, in ways so that anyone who understands pretty much has to say, Yes, it _has_ to be that way. It’s not that I don’t see the beauty in solving a math puzzle–I can appreciate that, but the rules ARE arbitrary IMO. Really–we have to balance an equation? Why? WTF is a constant and why do we use it and who decided what would be a constant? How does it matter? Can we solve things without it? What does 3.14 have to do with anything in my world (not that I mean to say that all math must be personally useful or significant, it’s just that no one ever explained WHY we needed the damned pi to begin with–I KNOW the Ancient Greeks “discovered” it–AND?) Who says the product of two negative numbers is a positive one? That does NOT make logical sense at all. Surely multiplication should work the same on the “other end” of the “range” of numbers, that is, -4 x-4 (should)=-16? I wish I excelled in math. I wish it came naturally to me. It doesn’t . I struggle. Never ask me to do anything remotely complicated with money (as in collecting cash or splitting a bill more than 3 way). I can’t do it well or easily or correctly. I cannot figure out word problems–I do not know what the writer of the problem is looking for after about 5th grade level word problems. I have a graduate degree and know I am intelligent, yet I cannot do basic HS math. I can (and enjoy) graphing x,y stuff, but (another example) I cannot identify which is the divisor, the dividend or the quotient. No clue. These are just examples. In studying for the GRE, I decided (since I had scored so low on a sample pretest that _my score did not register on the scale provided_ which means I got less than 11 correct, IMS), to just follow their damned rules and not try to make sense of it. I did manage to score what would be a low C (I don’t recall my score offhand)–thank God I didn’t need a good math score to get into grad school! > [@](#): > > Sometimes, alas, math is taught in such a way that it doesn’t make sense, whether because the teacher doesn’t really understand it or doesn’t care or doesn’t think he can afford the time to explain. Yes. From the 5th grade student teacher who told that since I was so smart in English etc, that I MUST be good in math, too (this was the 1970s) to the 6th grade teacher who had to take all our time to help a special needs kid (long story) and so my questions were not answered, to the 7th grade math teacher who was batshit insane and used to turn red with rage and throw chalk/erasers and protractors at us, to the HS ones who said I really didn’t “need” math or the one who drank and suffered from the shakes in Trig class–I had my share of suck ass teachers. I also had ones who really tried to get some of this stuff to stick. > [@](#): > > In a [book I recently read](http://www.amazon.com/Whats-Math-Got-Subject-Important/dp/B001R23FNY/ref=sr_1_2?ie=UTF8&s=books&qid=1249859466&sr=1-2), I was intrigued to read that girls more often than boys find it important to understand _why_ math works. That is intriguing. Sorry is this seems rather intense. I have intense feelings about math. I am frustrated and resentful that I cannot seem to acquire better math skills–not that I’m trying on a daily basis, mind. 🙂 ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 10, 2009, 4:41am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/47 "2009-08-10T04:41:32Z")
> [@eleanorigby](#): > > IReally–we have to balance an equation? Why? WTF is a constant and why do we use it and who decided what would be a constant? How does it matter? Can we solve things without it? What does 3.14 have to do with anything in my world (not that I mean to say that all math must be personally useful or significant, it’s just that no one ever explained WHY we needed the damned pi to begin with–I KNOW the Ancient Greeks “discovered” it–AND?) Who says the product of two negative numbers is a positive one? That does NOT make logical sense at all. Surely multiplication should work the same on the “other end” of the “range” of numbers, that is, -4 x-4 (should)=-16? If the equation isn’t balanced, then it’s false. 2 + 3 = 5. 2 = 5 - 3. But if we only take the 3 away from one side, then we get 2 = 5, which is false. A constant is simply a number that doesn’t change. X + 2 = 5. 2 is 2. It doesn’t change. Pi may not be useful to you, but it is for many people for many things. Even I use pi from time to time. For multiplying a negative, switch it to English: ‘I did not not eat the pie.’ You either ate it, or you didn’t. If you didn’t not eat it, then you did. So a negative times a negative is a positive. I am not a math person. I feel your frustration, believe me. I struggled. But if you put things into language terms, it can help. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 10, 2009, 4:47am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/48 "2009-08-10T04:47:26Z")
> [@Cunctator](#): > > It just means manipulating the equation until you have a perfect square on one side. An example (admittedly very easy, because you can factorise it at a glance anyway): > > x[sup]2[/sup]-2x-8=0 > > x[sup]2[/sup]-2x=8 > > x[sup]2[/sup]-2x+1=9 > > (x-1)[sup]2[/sup]=9 > > (x-1)=3 or -3 > > x=4 or -2 > > Once you’ve had to use this method lots of times on more complicated quadratics, you can derive the general formula by completing the square on ax[sup]2[/sup]+bx+c=0 at the drop of a hat. That makes perfect sense, and now I remember we did learn that in school. ---
**Author:** ![Dr.Love](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@Dr.Love](https://boards.straightdope.com/u/Dr.Love)\ **Post date:** [August 10, 2009, 5:21am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/49 "2009-08-10T05:21:42Z")
> [@eleanorigby](#): > > Arithmetic, is very useful, as are some basic equations such as distance=rate x time, but other than that, it is not useful or logical to me. > > \ > > Who says the product of two negative numbers is a positive one? That does NOT make logical sense at all. Surely multiplication should work the same on the “other end” of the “range” of numbers, that is, -4 x-4 (should)=-16? Believe it or not, the equation “distance = rate x time” is the most compelling reason why “negative x negative = positive.” At least, in the world as I see it. I can try to explain: Suppose there is a highway that starts at your city with mile zero. That is, if you leave the city along this highway, you first see mile marker 1, then mile makrer 2, etc. Suppose you’ve left your city along this highway, travelling at 60 mph the whole time, and right now you are passing mile marker 180. Your destination is another 200 miles down the highway. The first question: where will you be two hours from now? Using your equation above, distance = rate x time, so distance = 60 mph x 2 hours = 120 miles. You’re already at mile marker 180, so in two hours you’ll be at marker 180 + 60 mph x 2 hours = 180 + 120 = 300. The second question: where were you two hours ago? Again, using your formula, we get 60 mph x 2 hours = 120 miles. But this time, you’re 120 miles back, so you were at mile marker 180 - 120 = 60. Now, in question one we wrote “two hours in the future” as “2 hours”. It stands to reason that “two hours in the past,” the opposite of “two hours in the future,” would be represented as “-2 hours.” Just using the fact that “-” is the opposite of “+”. So using your distance equation, we should have 180 + 60 mph x -2 hours = 180 + (-120) = 180 - 120 = 60 miles marker. With me so far? The central idea is that _positive and negative are directions_. For questions three and four, you are now coming back home from your destination. But you’re still travelling at 60 mph, and still passing mile marker 180. The third question: where will you be in two hours? Same reasoning in question 1, you’ll be 120 miles ahead of where you are, but you’re travelling the opposite direction of the mile markers, so the marker you’re passing will be 180 - 120 = 60. Since you’re travelling the opposite direction, the “rate” you want to use is -60 mph. So the equation is 180 + -60 mph x 2 hours =180 - 120 = 60. The fourth (and final) question: where were you two hours ago? Obviously, you were at mile marker 300. The equation must be 180 + -60 mph x -2 hours = 300. And the _only_ way that this works out is if -60 mph x -2 hours = +120. And that’s it. All the rules about multiplying signed numbers come about from the formula “distance = rate x time”, and applying some common sense. ---
**Author:** ![cerberus](https://avatars.discourse-cdn.com/v4/letter/c/71e660/32.png) [@cerberus](https://boards.straightdope.com/u/cerberus)\ **Post date:** [August 10, 2009, 8:05am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/50 "2009-08-10T08:05:33Z")
REA Problem Solvers ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [August 10, 2009, 8:26am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/51 "2009-08-10T08:26:10Z")
> [@eleanorigby](#): > > WTF is the quadratic equation FOR? Parabolas. They describe trajectories of objects in a vacuum…which must be corrected of course for real world friction etc. but hey. Also, parabolic microphones, parabolic mirrors…I think a lot of telecom stuff WRT satellites must depend on them. ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [August 10, 2009, 8:57am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/52 "2009-08-10T08:57:08Z")
Surely multiplication should work the same on the “other end” of the “range” of numbers, that is, -4 x-4 (should)=-16? [/QUOTE] You’ve posed many good questions…I want to leave some for others but I’m allowing myself one more. 😉 Donald Trump’s daughter said she was walking down the street with him one day, before he made it big, and he saw a homeless guy. He said something like, “That man is worth $100M more than me.” The guy may have had a personal net worth of $0, but Trump was in the hole, big time. 1. You have $5 in one pocket, $5 in another. $5 x 2 =$10. 2. You owe friend A $5, same to friend B. -$5 x 2=-$10. Two friends owe you $5…treat that as both positive like in example 1 if you like. But if you treat a debt as a negative, and you don’t owe it to two people (they owe it to you), then it’s like you owe it to -2 people. -$5 x -2 people=$10. You’ll be $10 to the good either way you calculate it. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [August 10, 2009, 9:11am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/53 "2009-08-10T09:11:44Z")
I just want to offer my sympathy to the OP. Back in secondry school (high school), I scored highest in my year in a maths exam. I didn’t even feel like maths required any effort, it just came naturally. But I didn’t take my maths further than high school level, and now need to do so. And in the intervening 14 years, it seems my brain has atrophied! I’m slow to pick up maths concepts, and quick to forget what I’ve learned. ---
**Author:** ![Mogle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mogle/32/12021_2.png) [@Mogle](https://boards.straightdope.com/u/Mogle)\ **Post date:** [August 10, 2009, 11:08am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/54 "2009-08-10T11:08:24Z")
> [@eleanorigby](#): > > Arithmetic, is very useful, as are some basic equations such as distance=rate x time, but other than that, it is not useful or logical to me. WTF is the quadratic equation FOR? Quadratic equations are not for any one thing, it’s simply a name given to second order polynomial equations, distance=rate x time is a first order polynomial equation. The thing about d = r_t is that it assumes the speed is constant_ when in reality it rarely is, so we might want to add a constant acceleration in there. An object’s speed(assuming constant acceleration) at any given moment is equal to its acceleration \* time + initial velocity. So the rate in the first equation is r = a_t+v[sub]Initial[/sub]. This means that d=(a_t+v[sub]Initial[/sub])_t = a_t[sup]2[/sup]+v[sub]Initial[/sub]\*t , and now we’ve turned distance=rate x time into a quadratic equation describing the distance travelled by, say, an object falling in a vacuum. 🙂 > [@](#): > > Who says the product of two negative numbers is a positive one? That does NOT make logical sense at all. Surely multiplication should work the same on the “other end” of the “range” of numbers, that is, -4 x-4 (should)=-16? [This video](http://www.youtube.com/watch?v=hLm5lRxt1rE) has a fairly good explanation and rigid proof. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [August 10, 2009, 11:48am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/55 "2009-08-10T11:48:01Z")
> [@eleanorigby](#): > > WTF is the quadratic equation FOR? To some extent, it’s a tool that you need in the toolbox for tackling some tougher math. I’ve been taking a course in applied mathematics, and I’ve seen quadratics turning up all over the place, such as in how to work out the behaviour of a weight on the end of a spring. This is important if, for instance, you want to work out how stiff the springs in your car ought to be and how much damping to give them. You want to smooth out the bumps in the road, but you don’t want your car to still be bouncing up and down half a minute after the bump. > [@eleanorigby](#): > > It’s not that I don’t see the beauty in solving a math puzzle–I can appreciate that, but the rules ARE arbitrary IMO. Really–we have to balance an equation? Why? WTF is a constant and why do we use it and who decided what would be a constant? How does it matter? Can we solve things without it? What does 3.14 have to do with anything in my world (not that I mean to say that all math must be personally useful or significant, it’s just that no one ever explained WHY we needed the damned pi to begin with–I KNOW the Ancient Greeks “discovered” it–AND?) You have to balance an equation because that’s what an equation _is_ - two things on opposite side of an equals sign. It’s like putting stuff in the pans of a balance scale. Once they’re balanced, if they’re to stay balanced then you must do the same to both sides - whether that means adding a pound to both sides, doubling both sides, or whatever. Nothing arbitrary about it whatever. A constant is a “magic number” that can be derived by experimentation. How long does it take to boil a pint of water with a 1kW kettle? That depends not only on the mass of water (sixteen ounces in US measure, I believe) but on how hard it is to heat water - a certain amount of heat must be put in for every degree change in temperature. If you were to fill the kettle with pure alcohol, the answer would be different. The difference between a pint of water and a pint of alcohol, in this case, is the _constant_ known as _specific heat_ - there are many others. Can you solve things without it? Yes, but you have to reinvent the wheel each time - if you don’t know the constant, you can’t solve the equation (specific heat times mass times temperature increase equals amount of heat to put in), so you have to measure instead. Or how much does a copper bar expand when heated? There’s a constant for that - proportional increase per degree, known as “coefficient of expansion”. Pi is a constant - the circumference of a circle divided by the diameter. That’s always the same number no matter how big or how small the circle. And if you want to be able to work out how fast your car engine needs to turn to propel yourself at a certain speed - not necessarily your problem, but the designer’s - then knowing about pi is the least of your worries. > [@eleanorigby](#): > > Who says the product of two negative numbers is a positive one? That does NOT make logical sense at all. Surely multiplication should work the same on the “other end” of the “range” of numbers, that is, -4 x-4 (should)=-16? And another example. Let’s assume you and I have bank accounts with overdraft facilities, so our bank balances can go below zero. Let’s assume your daily pay from me is the only thing presently affecting your bank balance. Now… Today you have $0. I pay you $5 per day. How much money do you have in five days’ time? 5 days x $5/day = $25. Today you have $0. I charge you $5 per day (that’s the same as paying you -$5 per day). How much money do you have in five days’ time? 5 days x -$5/day = -$25. Today you have $0. I pay you $5 per day. How much money did you have five days ago? -5 days x $5/day = -$25. Today you have $0. I charge you $5 per day (that’s the same as paying you -$5 per day). How much money did you have five days ago? -5 days x -$5/day = $25. ---
**Author:** ![Shirley\_Ujest](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shirley\_Ujest](https://boards.straightdope.com/u/Shirley_Ujest)\ **Post date:** [August 10, 2009, 12:09pm UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/56 "2009-08-10T12:09:55Z")
> [@Johnny\_L.A](#): > > The lottery… > > I call it ‘a tax on people who are bad at math’. **When** I win BIG, I shall laugh heartily. -------\>has math anxiety. ---
**Author:** ![ivylass](https://avatars.discourse-cdn.com/v4/letter/i/9de053/32.png) [@ivylass](https://boards.straightdope.com/u/ivylass)\ **Post date:** [August 10, 2009, 5:58pm UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/57 "2009-08-10T17:58:28Z")
Congruency and betweenness…(I’m learning the very very very basics of geometry, with triangles. Boy, people are fascinated by triangles.) ---
**Author:** ![eleanorigby](https://avatars.discourse-cdn.com/v4/letter/e/ee7513/32.png) [@eleanorigby](https://boards.straightdope.com/u/eleanorigby)\ **Post date:** [August 11, 2009, 1:11am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/58 "2009-08-11T01:11:50Z")
Thank you all for your responses. I can’t say that your explanations clicked with me, but I do appreciate the effort. 🙂 It is nice to know what quadratics are for, but they were not a big problem for me in math. I LIKED being told how to solve an equation and then doing it endlessly. It is how that particular formula was created and how it was “discovered” that eludes me–I also cannot seem to figure out just when to use what formula in RL. I am a simple person. 😛 What gets me about math is 1). you’re supposed to (somehow) remember all these different formulae and drag them out when needed and 2). you’re supposed to know which formula to use when. As if… chance is a fine thing! I really like d=r x t because it makes sense to me and teenage me could tie it to something concrete (like a road trip). Other things are more abstract and therefore more problematic for me (and others, I’m sure): sine and cosine; base 8 or base 2; prime numbers (which I find interesting, but have no clue if they’re useful in any practical sense)… I can’t tell you what all I find perplexing because I have forgotten what most it is called. It’s been 30 years since HS math. I do appreciate that many disciplines use pi. I still don’t know WHY they use pi or how pi is so special to our understanding of our world, but that’s ok. Answer me this: why in some calculations do we suddenly have to multiply by 1000 or stick 60 in, especially when they cancel one another out? (not that 60 and 1000 cancel one another out–I’m using 2 different examples to make one point). Like this formula for calculating IV drips (now done by the computer in the IV pump, but still…) (dose/volume x 1000)/60/kilograms= dose/cc. There are other formulas, but I cannot find them just now–I used to have them all in a small book that fit in my pocket and I used them religiously (and accurately) to calc drip dosages and drug dosages for pts. I just never understood how those particular formulae were the right ones, if you follow me. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [August 11, 2009, 1:30am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/59 "2009-08-11T01:30:10Z")
> [@eleanorigby](#): > > Answer me this: why in some calculations do we suddenly have to multiply by 1000 or stick 60 in, especially when they cancel one another out? (not that 60 and 1000 cancel one another out–I’m using 2 different examples to make one point). > > Like this formula for calculating IV drips (now done by the computer in the IV pump, but still…) > > (dose/volume x 1000)/60/kilograms= dose/cc. > > There are other formulas, but I cannot find them just now–I used to have them all in a small book that fit in my pocket and I used them religiously (and accurately) to calc drip dosages and drug dosages for pts. I just never understood how those particular formulae were the right ones, if you follow me. I’m not familiar with those particular formulas, but I’m guessing that they’re conversion factors. (Grams and kilograms, for example, differ by a factor of 1000, and second and minutes differ by a factor of 60.) You might be able to use [dimensional analysis](http://www.alysion.org/dimensional/fun.htm) to make sense of such formulas. ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [August 11, 2009, 2:20am UTC](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779/60 "2009-08-11T02:20:07Z")
Here are some quotes about math that you might appreciate. Bertrand Russell, [Mathematics and the Metaphysicians](http://books.google.com/books?id=8dWZc2qWTtcC&lpg=PA74&ots=AT1UKv0KhP&dq=Mathematics%20and%20the%20Metaphysicians&pg=PA74#v=onepage&q=&f=false), collected in _Mysticism and Logic_. > [@](#): > > Pure mathematics consists entirely of such assertions as that, if such and such a proposition is true of **anything** , then such and such another proposition is true of that thing. > > It is essential not to discuss whether the proposition is really true, and not to mention what the anything is of which it is supposed to be true. Both these points would belong to applied mathematics. > > We start, in pure mathematics, from certain rules of inference, by which we can infer that **if** one proposition is true, then so is some other proposition. These rules constitute the major part of the principles of formal logic. We then take any hypothesis that seems amusing, and deduce its consequences. **If** our hypothesis is about **anything** and not about some one or more particular things, then our deductions constitute mathematics. > > Thus mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true. > > People who have been puzzled by the beginnings of mathematics will, I hope, find comfort in this definition, and will probably agree that it is accurate. James M. Barrie, _Quality Street_, act II. > [@](#): > > Susan: What is algebra exactly; is it those three-cornered things? > > Phoebe: It is x minus y equals z plus y and things like that. And all the time you are saying they are equal, you feel in your heart, why should they be. [Previous page](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779.md?page=2) [Next page](https://boards.straightdope.com/t/im-doing-math-again-and-my-head-hurts/505779.md?page=4)