## Answers: Week of November 30th

**Problem #1:** How many two digit numbers are there (i.e. between 10 and 99) where the sum of that number’s digits is also a two digit number? (for example, 87 would be 8+7=15)

Answer: 45

**Problem #2:** (hard) How many *three*-digit numbers are there where the sum of that number’s digits is a two-digit number?

Answer: 735