What Is Factor?
A factor of a number is a whole number that divides into it with nothing left over. Every number has at least two factors, 1 and itself, and most have several more. Factors are the basis for finding a GCF, an LCM, or a prime factorization.
Example
The factors of 12 are 1, 2, 3, 4, 6, and 12, since each of those divides evenly into 12.