From Mathcounts Target 2018:
- A 4-up number is defined as a positive integer that is divisible by neither 2 nor 3 and does not have 2 or 3 as any of its digits. How many numbers from 400 - 600 inclusive are 4-up numbers?
So I tried to find the complement, which is a number that is either divisible by 2 or 3 or has 2 or 3 as a digit. This I could calculute using PIE. But then I ran into some nasty casework for the intersection of the two sets: when the number is divisble by 2 or 3 and has 2 or 3 as a digit.
Any help would be great. Thanks.