Resources and Tools for Elementary Math Specialists and Teachers

To GCD or Not to GCD?

This discussion is part of a collection:Getting Off to a Good Start with Fractions

Many elementary texts have inserted basic topics from number theory between whole number and fraction arithmetic. Obviously, a working knowledge of primes, GCD and LCM are helpful in making the simplifying of fractions and the finding of common denominators more efficient.

Are they also help in understanding fractions conceptually? Do these topics pay benefits in other areas in the curriculum? Do some school math programs treat these as optional topics, or push them to the end of a school year? Do some teachers need a deeper understanding of them?


It is essential to have an understanding of LCM and GCF in order to solve some problems. In my experience they have always been taught as part of the fraction units or when teaching primes and factorization. I have encountered some teachers who like to teach shortcuts to find GCD, but in my opinion this does not add to their conceptual knowledge of fractions.