# 5 - 1 \* 4 - 3 + 6 / 8 = 7 **URL:** \ **Category:** Factual Questions\ **Created:** [July 27, 2003, 2:24pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259 "2003-07-27T14:24:48Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Tabby\_Cat](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Tabby\_Cat](https://boards.straightdope.com/u/Tabby_Cat)\ **Post date:** [July 27, 2003, 2:24pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/1 "2003-07-27T14:24:48Z")
No, it’s not a BODMAS question. Apparently, this question was given to one of my Secondary school (That’s probably high school) friends: Given the equation 5 - 1 \* 4 - 3 + 6 / 8 = 7 insert the brackets to validate this equation. I’m assuming that this includes using brackets to multiply (For example, 5(4) = 20) since without this, there aren’t many permutations. I’ve no success with this, at all. What kind of techniques are even applicible to this sort of question?! Kind help of any sort is requested. I even tried running a simulation on Excel, but I calculate 1.667 \* 10e13 possible permutations of the brackets, and gave up. 😃 (FTR, going to college this year. And I’m stumped! Stamp out my ignorance, please.) ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 27, 2003, 2:46pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/2 "2003-07-27T14:46:20Z")
(5-1)_(4-3+(6/8)) (4)_(4-3+3/4) 16-12+3=7 ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 27, 2003, 2:47pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/3 "2003-07-27T14:47:21Z")
(You don’t really need the () around the 6/8 that just happens by order of operations.) ---
**Author:** ![Tabby\_Cat](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Tabby\_Cat](https://boards.straightdope.com/u/Tabby_Cat)\ **Post date:** [July 27, 2003, 3:04pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/4 "2003-07-27T15:04:06Z")
> [@](#): > > _Originally posted by Joey P \* > \*\*(5-1)_(4-3+(6/8)) > (4)\*(4-3+3/4) > 16-12+3=7 \*\* Eh? Don’t quite get it. (4-3+6/8) gives me **1/4** , not… well, neither 12 nor 3. Or 16. Your equation gives me a result of 1. Can’t be right… Hmm. ---
**Author:** ![Jon\_the\_Geek](https://avatars.discourse-cdn.com/v4/letter/j/bbce88/32.png) [@Jon\_the\_Geek](https://boards.straightdope.com/u/Jon_the_Geek)\ **Post date:** [July 27, 2003, 3:07pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/5 "2003-07-27T15:07:47Z")
There are two ways to look at that last step. 1. Multiply the 4 through (that’s how Joey showed it): (4)\*(4-3+3/4) 16-12+3=7 2. Evaluate (4-3+3/4) first: 1 + 3/4 = 7/4 4 \* (7/4) = 7 ---
**Author:** ![TBone2](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@TBone2](https://boards.straightdope.com/u/TBone2)\ **Post date:** [July 27, 2003, 3:11pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/6 "2003-07-27T15:11:05Z")
> [@](#): > > \*Originally posted by Tabby\_Cat \* > \*\*Eh? Don’t quite get it. > > (4-3+6/8) gives me **1/4** , not… well, neither 12 nor 3. Or 16. Your equation gives me a result of 1. > > Can’t be right… Hmm. \*\* Try again. 4-3+6/8 is 1 3/4, if you do it in correct algebraic order. ---
**Author:** ![Tabby\_Cat](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Tabby\_Cat](https://boards.straightdope.com/u/Tabby_Cat)\ **Post date:** [July 27, 2003, 3:35pm UTC](https://boards.straightdope.com/t/5-1-4-3-6-8-7/191259/7 "2003-07-27T15:35:08Z")
D’oh!! Thank ye very much. It seems I should go back to grade school. I can’t believe I just did that!~!! I can integrate, differentiate, calculate polar cordinates… And can’t get my plus and minus signs in order. :smack: