A factor divides a number exactly. The greatest common factor of two numbers is the biggest factor they share. In the module, the shared factors are highlighted in both columns, and the largest is the GCF.

A multiple is what you get when you multiply by a whole number. The least common multiple is the first multiple the two lists share.

Factoring a sum pulls the shared factor out front: 36 + 8 = 4 × 9 + 4 × 2 = 4 × (9 + 2). That is the distributive property in reverse.