20 of them.
8
20 if you include 100, 19 if you don't.
Oh, dude, let me break it down for you. So, we start at 21 because it's the first number between 20 and 50 that's divisible by 3, and then we just keep adding 3 until we hit 48. So, that gives us 10 numbers in total. Easy peasy, right?
Remember 1 is not a prime number because it is only divisible by itself. 2, 3, 5, 7, 11, 13, 17, 19 These are the prime numbers between 0 and 20. In short, there are 9 prime numbers between 0 and 20.
20
Nine of them are evenly divisible by 5, if you include 20 and 60.
set of odd numbers divisible by 2 between 10 and 20
20 of them.
8
No number between 20 and 40 is divisible by all 4 numbers. The smallest number divisible by all 4 of those numbers is: 56
20 if you include 100, 19 if you don't.
6 12 18
There are 9 numbers evenly divisible by 10 : 10, 20, 30, 40, 50, 60, 70, 80, and 90
To be divisible by both 4 and 5, the number has to be divisible by 20. Therefore, there are 12 numbers between 1 and 240, inclusive, which are divisible by 4 and 5: 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240.
15
15