
From Marcel: Hello. My question is the following: Given the set {1,2...........10exp2019}, how many numbers from the set have the sum of its digits equal to 2?
I got some of them : 2 20 200 2000 20000 .......2. 10exp2018 11 110 1100 11000 110000....101 1010 10100 101000 1010000....10011 10010 100100 1001000 1010000.....10001 100010 1000100 10001000,,,,,,100001 1000010 10000100.......
My problem is that I have difficulty in finding a strategy to obtain the exact quantity of numbers. Please help me, thanks Answered by Penny Nom. 