# (Trick) Math/logic problem **URL:** \ **Category:** Factual Questions\ **Created:** [August 22, 2002, 10:41pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145 "2002-08-22T22:41:00Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![FIREMAN44](https://avatars.discourse-cdn.com/v4/letter/f/4af34b/32.png) [@FIREMAN44](https://boards.straightdope.com/u/FIREMAN44)\ **Post date:** [August 22, 2002, 10:41pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/1 "2002-08-22T22:41:00Z")
My fifth grader brought this question home for me to help her with and I am stumped! The problem is as follows; “Make 3 8s equal 7.” No further instructions or hints, any ideas? Thanks dopers!! ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [August 22, 2002, 10:54pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/2 "2002-08-22T22:54:05Z")
8 - 8/8 = 7 ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [August 22, 2002, 10:57pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/3 "2002-08-22T22:57:42Z")
Presumably, you’re allowed to use the standard arithmetic operations. So the question is asking you to make an arithmetic expression using three eights which is equal to 7. The answer’s below, but don’t look unless you’re stumped. [spoiler][symbol]If you allow squaring to be an arithmetic operation, then (8[sup]2[/sup] - 8)/8 is equal to 7. But I doubt that’s allowed. If you don’t allow squaring, 8 - 8/8 is equal to 7.[/symbol][/spoiler] ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 22, 2002, 11:00pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/4 "2002-08-22T23:00:33Z")
ultra’s answer is all Greek to me. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [August 22, 2002, 11:02pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/5 "2002-08-22T23:02:46Z")
The symbol font isn’t as useful–I forgot that it uses the same characters for numbers and arithmetic operators. And shame on you, **Nametag** … ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [August 22, 2002, 11:07pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/6 "2002-08-22T23:07:14Z")
Well, heck, as long as **FIREMAN44** looks at this, and not his daughter, what’s the harm? OK, OK, 50 lashes with a wet hornbook… :smack: ---
**Author:** ![FIREMAN44](https://avatars.discourse-cdn.com/v4/letter/f/4af34b/32.png) [@FIREMAN44](https://boards.straightdope.com/u/FIREMAN44)\ **Post date:** [August 22, 2002, 11:07pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/7 "2002-08-22T23:07:47Z")
Thanks Nametag & ultrafilter. I told her the truth, that you both are the heroes! So simple, but I could not think of the answer. Thanks again! I knew I could depend on you guys! ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [August 22, 2002, 11:23pm UTC](https://boards.straightdope.com/t/trick-math-logic-problem/125145/8 "2002-08-22T23:23:53Z")
Hornbook? No way, dude, it’s a noodle or nothing!