This puzzle seems very simple, but it confused you go astray!

Do you know how to count in your mind? Site
Take 1000. 40. Combine Combine More Combine 1000. 30. 1000. More Plus 20. Plus 1000. And plus 10.

What happened?

Answer:

5000 has turned out? Wrong. The correct answer - 4100. If you do not believe me, count on the calculator

! via factroom.ru