Rely solely on your thoughts to complete this task—no calculator or paper needed.
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.
