Discrete Mathematics
# Rule of Sum and Rule of Product

\(\)

When we write the integers from 1 to 100, how many times does the digit 9 appear?

Find the number of \(2\) digit numbers whose digit sum is a perfect square.

**Bonus question**: Can you generalize this for a \(N \times N \times N\) Rubik cube?

×

Problem Loading...

Note Loading...

Set Loading...