What is a number between 20 and 30 that has 2prime factors?

Answer 1

30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50

Answer 2

The perfect squares:

4: 1, 2 and 4

9: 1, 3 and 9

16: 1, 2, 4, 8 and 16

25: 1, 5 and 25

Answer 3

31, 37, 41, 43 and 47 have exactly 2 factors.

The others have more than 2.

Answer 4

2, 3, 5, 7, 11, 13, 17, 19, 23 and 29

Answer 5

The even numbers. 2, 4, 6 and so on.

Answer 6

The primes: 2,3,5,7,11,13,17 and 19.

Answer 7

31, 37, 41, 43, 47

Pick three.

Answer 8

22