maybe you could list the possible factor pairs?

Ah ... or, you could say that since the quotient is 4, it means that one of the numbers is 4 times the other ... so what you actually have is 4 times a number times the same number ... so, you divide 676 by 4 to get 169, and so 13 would be that same number multiplied to itself (so the other number would be 13 times 4) ... essentially, reduce it to one variable and "explain" it that way ... but if you're asking how to solve it, on paper, without using letters ... that's kinda tough ... use stars? haha (Or a question mark, maybe that will make more sense to him/her)

I'm not sure what grade 6 covers, I looked it up, this might be an introductory problem to using variables .... so maybe you just need to explain what the letter represent