# Math Help - divisors

1. ## divisors

How many numbers from 1 to 18,000, inclusive, are divisible by 20 or 3 or both?

2. $18000 = 900\cdot20$

So all the multiples of $20$ are $\{1\cdot20,2\cdot20,3\cdot20,\cdots,900\cdot20\}$

Hopefully you can see how many elements are in that set.

The case with $3$ follows the same way.