How many numbers between 11 and 90 are divisible by 7?

How many numbers between 100 and 500 are divisible by 4, 5 and 6?

How many numbers between 200 and 600 are divisible by 4, 5 and 6?

How many three-digit numbers are divisible by 5?

How many prime numbers are there between 1 and 50?

Two possible rational numbers between -2/3 and 1/2 are: