I've been trying to figure this stupid thing out all day.

Take 1,000 and add 40 to it.
Now add another 1,000. Now add 30. And another 1,000.
Now add 20. Now add another 1,000. Now add 10.
What's the total?


I keep coming up with 5000, but the answer says "Did you say 5,000? Sorry, that is incorrect. The correct answer is 4,100. (Read the question again...slowly and carefully)"

I don't get it.
There's no way I can come up with 4,100.
Am I missing something?