· 2 min read · Ages 9–12 · Grade 4 through Grade 6
LCM and HCF practice sheets with room to list the factors
She got stuck adding 3/4 and 5/6, not on the fractions but on finding 12. LCM hides inside other skills and deserves its own practice first.
The first time my daughter had to add 3/4 and 5/6, she got stuck, and not on the fractions. She could not find 12. Lowest common multiple is a skill that hides inside other skills, and it is worth practicing on its own for a couple of weeks before it is needed for something else.
What the sheet looks like
The LCM and HCF generator prints pairs of numbers and asks for the highest common factor, the lowest common multiple, a mix, or both for every pair. Three levels: easy with numbers to 20 for fourth grade, standard to 50, and challenge to 100 with some three-number problems for fifth and sixth. You can call it HCF, GCF or GCD to match whatever the textbook says. Pages hold 8 to 20 problems, and there is a working space option that leaves room under each problem for listing factors or multiples.
Why it works
- Listing the factors of 24 and 36 is the method, and the working space makes room for it. A sheet with only an answer box quietly tells kids to guess.
- Both-per-pair puts HCF and LCM of the same numbers side by side. After a few, a sharp kid notices that HCF × LCM equals the product of the pair.
- The naming option matters more than it should. A child who sees GCF at school and HCF at home thinks they are two different things.
Who it suits
Fourth graders start with HCF only at the easy level, and only once multiplication facts are fast; if they are not, the fact fluency drills are the step before. Sixth graders can take challenge level with three numbers and no working space. The whole point of LCM shows up the moment you go back to the fractions worksheet and add unlike denominators.
Two sheets a week for a fortnight is usually enough.