Use only your thoughts to complete this task rather than a calculator or paper.

THE QUESTION

THE ANSWER

Starting with 1000, add 40, then 1000, followed by 30, another 1000, then 20, another 1000, and finally add 10.

The total is:

1000 + 40 + 1000 + 30 + 1000 + 20 + 1000 + 10 = 4090.