A friend of mine posted this on FaceBook. Try it! =D I'll post the rest of it (I cropped out the answer) after a few people post what answers they get If you know it, don't spoil it!

I know, right?? I just tried it a couple different ways, like adding up all the 1000's, then adding the smaller numbers, but it still does it

I'd post my answer, but apparently that'd spoil it For more fun: http://www.flowgo.com/funny/1164_stupid-test.html

It comes out to two different things depending on how you do it. Its creepy! I'll post the rest of the pic now lol

I nailed it the first time. I added all the thousands then the tens. My mind works that way though, I had to add time all the time when I worked in t.v.:;dete

Take 1000 and add 40. = 1,040 Add 1000. = 2,040 Add 30 = 2,070 and then add 1000. = 3,070 Add 20. = 3,090 Add 1000 = 4,090 and then add 10. = 4,100 The 'trick' is in the way you do things in your head, in words, not in numbers. Most people tend to break the numbers down, for easier recall, such that: Take 1000 and add 40. = 1,040 => Ten Forty (in your head) Add 1000. = 2,040 => Twenty Forty Add 30 = 2,070 => Twenty Seventy and then add 1000. = 3,070 => Thirty Seventy Add 20. = 3,090 => Thirty Ninety Add 1000 = 4,090 => Forty Ninety and then add 10. = 4,100 => Brain 'complains'. The last numbers in your head were Forty Ninety, +10 becomes Forty One Hundred = The brain automatically ticks over and resets the count to 0, and increases to Fifty in your head, because of the break-down to 'simpler' numbers, the brain fails to recognise Forty One Hundred as a real number. For those that added it in full, i.e. One Thousand and Forty + ....., tend to get the correct answer of 4,100

I tried that, too, but I guess I didn't do it right (but I'm not a math whiz. My TI-89 is my best friend LOL)