This riddle must be done IN YOUR HEAD and NOT using paper and a pen.
Try it!
Take 1000 and add 40 to it. Now add another 1000.
Now add 30. And another 1000.
Now add 20. Now add another 1000. Now add 10.
What is the total?
Did you get 5000? Way to go... most of us do, join the crowd!
But you know what? We're all wrong!
The correct answer is actually 4100. Don't believe it? Check it with a calculator or on paper!
The brain sure knows how to play little tricks on us, doesn't it?