Rule of Sum and Rule of Product: Level 2 Challenges Practice Problems Online

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 $n \times n$ square with $n \geq 2$ ?

Find the number of $2$ digit numbers whose digit sum is a perfect square.

If you take a $3 \times 3 \times 3$ Rubik cube and break it up into the $3^3$ cubes, how many cubes would have stickers on exactly $2$ faces?

Bonus question: Can you generalize this for a $N \times N \times N$ Rubik cube?

9 26 3 27 8 12 6

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Rule of Sum and Rule of Product: Level 2 Challenges

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