Well, here's one someone just forwarded me... it's probably making the rounds of the Internets... There are other questions, but this is the only math-related one.

This must be done in your head only .
Do NOT use paper and pencil or a calculator. Try it.

Take 1000 and add 40 to it. Now add another 1000 . Now add 30 .
Add another 1000 . Now add 20 . Now add another 1000
Now add 10. What is the total?

(Highlight answer below)


Did you get 5000? The correct answer is actually 4100.