# Do this math problem in your head. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [October 28, 2008, 2:08pm UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932 "2008-10-28T14:08:40Z")\ **Posts on this page:** 20\ **Page:** 7
**Author:** ![sinjin](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@sinjin](https://boards.straightdope.com/u/sinjin)\ **Post date:** [October 29, 2008, 2:22am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/121 "2008-10-29T02:22:22Z")
> [@Idle\_Thoughts](#): > > Do not read any of the replies before you reply yourself with your answer. > Do not edit your reply please. > > Sorry for the annoying way this OP is set up (with all of the spoiler boxes), but I’m curious over what answer people will get. Again, hit reply and post your answer BEFORE you read any other answers in here. > > What is the number you wind up with? 4100 ---
**Author:** ![QuercusMax](https://avatars.discourse-cdn.com/v4/letter/q/8baadc/32.png) [@QuercusMax](https://boards.straightdope.com/u/QuercusMax)\ **Post date:** [October 29, 2008, 2:26am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/122 "2008-10-29T02:26:14Z")
1. But for a split second I thought 5000. 5000 “seemed” like it should be the answer, but obviously it’s not. ---
**Author:** ![Clothahump](https://avatars.discourse-cdn.com/v4/letter/c/51bf81/32.png) [@Clothahump](https://boards.straightdope.com/u/Clothahump)\ **Post date:** [October 29, 2008, 2:26am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/123 "2008-10-29T02:26:38Z")
4100 ---
**Author:** ![Morgyn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/morgyn/32/3041_2.png) [@Morgyn](https://boards.straightdope.com/u/Morgyn)\ **Post date:** [October 29, 2008, 3:24am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/124 "2008-10-29T03:24:45Z")
4100 ---
**Author:** ![papaw](https://avatars.discourse-cdn.com/v4/letter/p/b77776/32.png) [@papaw](https://boards.straightdope.com/u/papaw)\ **Post date:** [October 29, 2008, 3:30am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/125 "2008-10-29T03:30:28Z")
HMMM 5000. I’ve seen this somewhere, prolly got the wrong answer ---
**Author:** ![Rand\_Rover](https://avatars.discourse-cdn.com/v4/letter/r/db5fbb/32.png) [@Rand\_Rover](https://boards.straightdope.com/u/Rand_Rover)\ **Post date:** [October 29, 2008, 4:02am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/126 "2008-10-29T04:02:42Z")
4100 . . . 😕 ---
**Author:** ![Sefton](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Sefton](https://boards.straightdope.com/u/Sefton)\ **Post date:** [October 29, 2008, 4:05am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/127 "2008-10-29T04:05:26Z")
4100 ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [October 29, 2008, 4:11am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/128 "2008-10-29T04:11:28Z")
4,100 - why? ---
**Author:** ![Silophant](https://avatars.discourse-cdn.com/v4/letter/s/a698b9/32.png) [@Silophant](https://boards.straightdope.com/u/Silophant)\ **Post date:** [October 29, 2008, 4:16am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/129 "2008-10-29T04:16:09Z")
4100? ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [October 29, 2008, 4:33am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/130 "2008-10-29T04:33:31Z")
**8,963.2777[…]** Actually, I came up with 5000. Fuckin’ head games! I see now where it gets you, thanks to brewha. ---
**Author:** ![IGJoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/igjoe/32/5420_2.png) [@IGJoe](https://boards.straightdope.com/u/IGJoe)\ **Post date:** [October 29, 2008, 4:49am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/131 "2008-10-29T04:49:06Z")
4100, but I was very tempted to say 5000 after the last question. Had to think about it for a second. ---
**Author:** ![Between\_the\_Bars](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@Between\_the\_Bars](https://boards.straightdope.com/u/Between_the_Bars)\ **Post date:** [October 29, 2008, 5:15am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/132 "2008-10-29T05:15:14Z")
5000 ---
**Author:** ![E.Thorp](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@E.Thorp](https://boards.straightdope.com/u/E.Thorp)\ **Post date:** [October 29, 2008, 5:21am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/133 "2008-10-29T05:21:49Z")
OK, I’ve been good and not looked. 4100. ---
**Author:** ![Savannah](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@Savannah](https://boards.straightdope.com/u/Savannah)\ **Post date:** [October 29, 2008, 5:24am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/134 "2008-10-29T05:24:41Z")
I said 5000, my husband said 4100. Gee, he bugs me. ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [October 29, 2008, 9:29am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/135 "2008-10-29T09:29:42Z")
5000, until I decided there must be a trick here and went back to check. Interesting puzzle there. ---
**Author:** ![Carmady](https://avatars.discourse-cdn.com/v4/letter/c/f04885/32.png) [@Carmady](https://boards.straightdope.com/u/Carmady)\ **Post date:** [October 29, 2008, 9:56am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/136 "2008-10-29T09:56:00Z")
1. I was expecting a trick, but there didn’t seem to be one. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [October 29, 2008, 10:31am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/137 "2008-10-29T10:31:04Z")
> [@Idle\_Thoughts](#): > > I just realized something. > > When you put the mouse over the topic, you get a preview and the spoilers tags don’t show. > > In my opinion, this makes it much easier to get the right answer…because (like I said before) people see ALL of the numbers in one place, so they’re apt to just add together all of the 1000s first (getting 4000) and then add the 10, 20, 30, 40 together (getting 100) and then just add 4000 and 100. > > Go on, admit it if you did that. 🙂 I habitually just press ctrl + a to highlight everything, including the spoiler boxes, so I could see them all at once. Didn’t stop me from figuring wrong at first, so all bets are off as to what I’d have gotten highlighting them one by one… ---
**Author:** ![Cazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cazzle/32/75_2.png) [@Cazzle](https://boards.straightdope.com/u/Cazzle)\ **Post date:** [October 29, 2008, 10:34am UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/138 "2008-10-29T10:34:53Z")
4100 But I fell for it the first time I saw it, in 1999. ---
**Author:** ![Idle\_Thoughts](https://avatars.discourse-cdn.com/v4/letter/i/838e76/32.png) [@Idle\_Thoughts](https://boards.straightdope.com/u/Idle_Thoughts)\ **Post date:** [October 29, 2008, 12:31pm UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/139 "2008-10-29T12:31:51Z")
So it looks like the 4100s get it, although there are a large number of 5000s…which actually comforts me in a strange way to know that this “mind trick” of sorts still works even when people are reading it instead of hearing it. Thank you all for being honest in your answers, though. ---
**Author:** ![WormTheRed](https://avatars.discourse-cdn.com/v4/letter/w/bbe5ce/32.png) [@WormTheRed](https://boards.straightdope.com/u/WormTheRed)\ **Post date:** [October 29, 2008, 12:45pm UTC](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932/140 "2008-10-29T12:45:00Z")
5000 And apparently I fell for the trick ☹ Crap. [Previous page](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932.md?page=6) [Next page](https://boards.straightdope.com/t/do-this-math-problem-in-your-head/469932.md?page=8)