Divisiblilty & Prime Problems [GRE]?
If j is divisible by 12 and 10, is j divisible by 24? Answer by either saying yes, no, or Can't be determined. First I found the prime factors of both numbers (10: 5 * 2 and 12 : 3*2*2). Then I found out the prime factors of 24: 2*3*2*2, So I concluded from this since we need 3 2s and 1 3 the answer is yes. However the book states that the answer is can't be determined because one of the 2s can be redundant. I am not sure about this reasoning can anyone explain me why? Also if you have some reliable source please present it.