When we write the integers from 1 to 100, how many times does the digit 9 appear?
Which of the following expresses the correct formula for the number of unit squares with exactly 1 red side in an square with ?
Find the number of digit numbers whose digit sum is a perfect square.
If you take a Rubik cube and break it up into the cubes, how many cubes would have stickers on exactly faces?
Bonus question: Can you generalize this for a Rubik cube?