# What could possibly be the point in this grade 8 math exercise? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [September 13, 2010, 3:18pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609 "2010-09-13T15:18:59Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![etv78](https://avatars.discourse-cdn.com/v4/letter/e/d78d45/32.png) [@etv78](https://boards.straightdope.com/u/etv78)\ **Post date:** [September 13, 2010, 8:48pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/21 "2010-09-13T20:48:54Z")
This is why I disliked advanced math! Though my,“I’m never gonna use this!”, didn’t happen until I got to trig. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [September 13, 2010, 10:50pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/22 "2010-09-13T22:50:30Z")
> [@cwthree](#): > > Perhaps the point was to realize that if you do the brute-force thing for the values 1, 2, 3 and 5, you can then string those together to build _all_ of the other answers? Except for the prime numbers, everything else can be factored down to multiples of 1, 2, 3 and 5, and multiplication can be reduced to repeated adding. Prime numbers can be created by summing (but not factoring) as well. 77 begs to differ. But, also, that process won’t work with the stated rules, which are to use each of the numbers _once_. ---
**Author:** ![Hello\_Again](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hello\_Again](https://boards.straightdope.com/u/Hello_Again)\ **Post date:** [September 13, 2010, 11:01pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/23 "2010-09-13T23:01:08Z")
> [@etv78](#): > > This is why I disliked advanced math! Though my,“I’m never gonna use this!”, didn’t happen until I got to trig. This is not advanced math. This is where you use extremely simple principles of math, and apply them creatively. **Leaffan** just be careful about pushing towards “perfect” results when it is of no benefit. That way lies long-term math anxiety, and I speak from experience. If your daughter puts in a good honest effort, let her stop when she’s really stumped. “Stumped” happens, and its a healthy part of the learning experience. This is supposed to be a fun assignment where you think and experiment and try different things. The only person making this assignment take “8 hours to complete”, is you. Therefore, the assignment is not unreasonable, but maybe you are. ---
**Author:** ![cwthree](https://avatars.discourse-cdn.com/v4/letter/c/9de0a6/32.png) [@cwthree](https://boards.straightdope.com/u/cwthree)\ **Post date:** [September 13, 2010, 11:43pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/24 "2010-09-13T23:43:30Z")
> [@iamthewalrus\_3](#): > > > [@cwthree](#): > > > > Perhaps the point was to realize that if you do the brute-force thing for the values 1, 2, 3 and 5, you can then string those together to build _all_ of the other answers? Except for the prime numbers, everything else can be factored down to multiples of 1, 2, 3 and 5, and multiplication can be reduced to repeated adding. Prime numbers can be created by summing (but not factoring) as well. > > 77 begs to differ. > > But, also, that process won’t work with the stated rules, which are to use each of the numbers _once_. Feh. Both my math skills and my reading comprehension have gone to hell. ---
**Author:** ![Munch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/munch/32/5281_2.png) [@Munch](https://boards.straightdope.com/u/Munch)\ **Post date:** [September 14, 2010, 12:44am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/25 "2010-09-14T00:44:53Z")
> [@iamthewalrus\_3](#): > > 77 begs to differ. > > But, also, that process won’t work with the stated rules, which are to use each of the numbers _once_. 81 - 4 = 77 The rules do not state you must use every number once, merely that you can only use those 4 numbers. And since you can also use exponents (including roots) that adds quite a bit to it. ---
**Author:** ![Pai325](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Pai325](https://boards.straightdope.com/u/Pai325)\ **Post date:** [September 14, 2010, 12:45am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/26 "2010-09-14T00:45:57Z")
It sounds like fun to me, and you should approach it that way. If she’s got the whole week it’s not that bad. ---
**Author:** ![Pseudocode](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pseudocode](https://boards.straightdope.com/u/Pseudocode)\ **Post date:** [September 14, 2010, 5:27am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/27 "2010-09-14T05:27:43Z")
I think the idea is to use parts of previous answers to form the solutions for the next numbers. Here are my solutions for the first 11; I think you should be able to see some patterns clearly: 1. 8 - (√9 \* √4) - 1 2. 8 - √9 - 4 + 1 3. 8 - (√9 \* √4) + 1 4. 8 - √9 - √4 + 1 5. 9 - 8 + 4 \* 1 6. 9 - (8 / 4) - 1 7. 9 - (8 / 4) \* 1 8. 9 - (8 / 4) + 1 9. √9 \* ((8 / 4) + 1) 10. 9 + (8 / 4) - 1 11. 9 + (8 / 4) \* 1 etc. You can’t always reuse elements from the previous solution(s), but you usually can. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [September 14, 2010, 5:33am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/28 "2010-09-14T05:33:02Z")
These rote grinds things are an insanely tedious marathon for kids who are not math inclined. Almost every time I’ve ever taken these monster assignments at face value, and helped my kid grind them out (when they were in Jr High) it \*almost always \*turned out the teacher told the kids to do some far smaller subset of the problem, and my kids never wrote that part down. If it’s for real I’d simply send in a note saying “At the rate my child can factor these problems it will take her 8 hours to finish this homework assignment requiring 100 unique answers. This is an utterly unreasonable amount of homework. We need to have a conversation.” ---
**Author:** ![FuzzyOgre](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@FuzzyOgre](https://boards.straightdope.com/u/FuzzyOgre)\ **Post date:** [September 14, 2010, 5:56am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/29 "2010-09-14T05:56:29Z")
One day at my very boring job I decided to memorize my divisions table from 1/2 to 1/100. After that I got much better at arithmetic. In my mind it would have been better to do that than the 1-10s multiplication table we learned in school. At a certain point the patterns start jumping out at you. Which is I think the point of this exercise. ---
**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:** [September 14, 2010, 6:06am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/30 "2010-09-14T06:06:56Z")
> [@etv78](#): > > This is why I disliked advanced math! Though my,“I’m never gonna use this!”, didn’t happen until I got to trig. It’s hard to know that in advance though. I worked in video games for a number of years, and used triganometry almost daily. It’s something I wouldn’t have anticipated being useful (and now I think about it, I can’t remember why it comes up so often, but it does). on preview: oh yeah; it’s often when you need to work out where a point is on a circle. ---
**Author:** ![Grumman](https://avatars.discourse-cdn.com/v4/letter/g/43a26b/32.png) [@Grumman](https://boards.straightdope.com/u/Grumman)\ **Post date:** [September 14, 2010, 6:24am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/31 "2010-09-14T06:24:31Z")
> [@Leaffan](#): > > I’m pretty sure you need to use all 4 numbers in the equation. That’s easy: just multiply by the other numbers to the power of 0. 1. 1 \* (4+8+9)^0 ---
**Author:** ![needscoffee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/needscoffee/32/1076_2.png) [@needscoffee](https://boards.straightdope.com/u/needscoffee)\ **Post date:** [September 14, 2010, 6:38am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/32 "2010-09-14T06:38:28Z")
> [@Grumman](#): > > > [@Leaffan](#): > > > > I’m pretty sure you need to use all 4 numbers in the equation. > > That’s easy: just multiply by the other numbers to the power of 0. > > 1. 1 \* (4+8+9)^0 Zero isn’t one of the included numbers. ---
**Author:** ![sandra\_nz](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@sandra\_nz](https://boards.straightdope.com/u/sandra_nz)\ **Post date:** [September 14, 2010, 7:16am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/33 "2010-09-14T07:16:19Z")
They’re being prepped to appear on [Countdown](http://en.wikipedia.org/wiki/Countdown_(game_show)#Numbers_round). ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [September 14, 2010, 8:51am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/34 "2010-09-14T08:51:03Z")
I actually think that assignments like these only really tell you who enjoys math and who doesn’t. At eighth grade, nobody who doesn’t enjoy math will actually bother to spend any length of time on an optional assignment. The kids that will learn anything are going to be the ones that already good enough at math that they didn’t need this “lesson,” whatever it is. I do know that, despite always being the guy who got the highest grades in math class, I would feel incredibly stupid if I didn’t get one that someone else did. ---
**Author:** ![Scougs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scougs/32/3158_2.png) [@Scougs](https://boards.straightdope.com/u/Scougs)\ **Post date:** [September 14, 2010, 10:17am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/35 "2010-09-14T10:17:37Z")
> [@sandra\_nz](#): > > They’re being prepped to appear on [Countdown](http://en.wikipedia.org/wiki/Countdown_(game_show)#Numbers_round). Ah, but in Countdown you don’t have to use all the numbers. I should know, I’ve got the teapot to prove it. ---
**Author:** ![sandra\_nz](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@sandra\_nz](https://boards.straightdope.com/u/sandra_nz)\ **Post date:** [September 14, 2010, 11:11am UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/36 "2010-09-14T11:11:08Z")
> [@Scougs](#): > > > [@sandra\_nz](#): > > > > They’re being prepped to appear on [Countdown](http://en.wikipedia.org/wiki/Countdown_(game_show)#Numbers_round). > > Ah, but in Countdown you don’t have to use all the numbers. > > I should know, I’ve got the teapot to prove it. :eek: You’re my new hero! ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [September 14, 2010, 12:48pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/37 "2010-09-14T12:48:22Z")
Are you sure this isn’t an 8th grader trying to get his homework done 😃 ??? ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [September 14, 2010, 1:04pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/38 "2010-09-14T13:04:56Z")
> [@Markxxx](#): > > Are you sure this isn’t an 8th grader trying to get his homework done 😃 ??? If so, I registered here in grade three. 😃 Anyway, with my wife’s help she’s almost all the way through this. Personally, I do NOT think that giving appreciable help to the kid-o in this case was the right thing to do, but my wife thought it was too much to ask of a 13 year old. I wonder how many other parents are also doing this for their kids? (Hmm… parents helping with homework could be good separate thread.) ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [September 14, 2010, 2:01pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/39 "2010-09-14T14:01:10Z")
If there’s a higher point to this exercise, I think that it’s trying to think in terms of polynomials. I did notice that the given numbers are 1, 2, 2², 2³, and 3². It’d be interesting to see a proof that these numbers are necessary and sufficient, and a generalized method of using them to produce 1 through 100. ---
**Author:** ![Zeriel](https://avatars.discourse-cdn.com/v4/letter/z/58956e/32.png) [@Zeriel](https://boards.straightdope.com/u/Zeriel)\ **Post date:** [September 14, 2010, 8:02pm UTC](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609/40 "2010-09-14T20:02:44Z")
Nearly all assignments of this type, in my experience, are to build competence with the basics by repetition, so that when she gets more advanced stuff to do she can concentrate on the novel/difficult aspects rather than worrying about number manipulation. Frankly I would guess the entire assignment would have taken me about two hours in 8th grade, but I’m particularly math-inclined. [Previous page](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609.md?page=1) [Next page](https://boards.straightdope.com/t/what-could-possibly-be-the-point-in-this-grade-8-math-exercise/553609.md?page=3)