The even numbers between 40 and 50 are: 42, 44, 46 and 48.

Factors are the numbers you multiply together to get another number:

42 = 1*2*3*7

42 has the factors: 1,2,3,7,6,14,21 and 42

44 = 1*2*2*11

44 has factors: 1,2,11,4,22 and 44

46 = 1*2*23

46 has factors: 1,2,23 and 46

48 = 1*2*2*2*2*3

48 has factors: 1,2,3,4,6,8,12,16,24 and 48

The answer is, the even number between 40 and 50 that has four factors is 46.