Originally posted by kedaman
3- How many positive integers less than 1,000,000 have exactly one digit equal to 9 and have a sum of digits equal to 13?
9*(8+8*7+8C2)=828
Why is that? I manually checked all numbers below 1000000 and came up with 420. DerFarm also arrived at this conclusion. COuld you elaborate on how you arrived at this answer?