(m • n)-1 =
What is the answer to this question?

Fill in m and n with numbers then minus by one

A lumber is 104 inches long. If Ivan wants to saw it into pieces of 12-inch fences, then he needs to split 104 into 12's. 104 divided by 12 is 8.66... which means at most he can make 8.66... fences, but there aren't things such as .66... fences. So Ivan can saw 8 fences of 12 inches long.