In math, factorization is when you break a number down into smaller numbers that, multiplied together, give you that original number. When you split a number into its factors or divisors, that's factorization. The word factorization comes from factor, which has had a mathematical meaning since the 1600s—key Concepts. The most significant common factor, or GCF, can be factored out of a polynomial. Trinomials with leading coefficient one can be factored by finding numbers that have a product of the third term and a sum of the second term. Trinomials can be factored using a process called factoring by grouping.