What is the least positive integer multiple of 30 that can be written with only the digits 0 and 2?
Let $M$ be the least positive multiple of 30 that can be written with only the digits 0 and 2. First, $M$ is a multiple of 10, so its units digit must be 0. $M$ is also a multiple of 3, which means the sum of its digits must be a multiple of 3. Therefore, we must take at least  three 2's. Since $M$ is minimal, we take exactly three 2's and do not have any additional 0's: $M=\boxed{2220}$.