My Three Sons

Here is an extra credit problem from a fourth grader's homework. If you are still in fourth grade, it's understandable that you won't get the answer. After all, it is extra credit, implying it is beyond some, but not all, fourth grade students). However, if you are in 5th grade or above, I'm sure it will be a piece of cake. Here it is:

A woman has three sons. Her friend asks her how old they are, and she replies, "If you multiply their ages together, you get 72". The friend thinks about it for a bit, and he says, "I cannot figure out their ages." So she replies, well, the sum of their ages equals my house number. The friend looks up the woman's house number, but eventually comes back and says, "I still do not know their ages." Finally, the woman says, "Well, my oldest son is named Arnold". Then the friend says with certainty, "I now know their ages."

What are their ages?


Keep in mind, this is a fourth grade problem, so their ages are all whole numbers, (don't even think about fractions...what are you, a sixth grader or something?!). Good luck, kiddies!