I am looking at a question from an assignment and it asks

So for a.2. Consider 4-digit numbers from 1000 to 9999, inclusive.

- How many are divisible by 5 ?
- How many are divisible by 9 ?
- How many are divisible by both 5 and 9 ?
- How many are divisible by either 5 or 9 ?

If it is divisible by 5 it ends with either 0 or 5.

so 2 out of the 10 possible last digits would be ones divisible by 5.

and there would be 899 groups of these 10 last digit numbers.

would 1798 be divisible by 5?

Sorry but my math intuition is so bad LOL.