Factoring & Prime Factors Worksheets
Factors and multiples, prime and composite numbers, prime factorisation, greatest common factor and least common multiple.
Grade 3
Grade 4
- Divisibility RulesG4, G5 · Factoring & Prime Factors
- Factors of a NumberG4 · Factoring & Prime Factors
- Prime and Composite NumbersG4, G5 · Factoring & Prime Factors
Grade 5
The building blocks of whole numbers
Factors are numbers that multiply to make another number; multiples are what you get by counting in steps of a number. Primes (2, 3, 5, 7, 11…) have exactly two factors and cannot be broken down, while composite numbers can. Every whole number greater than 1 is either prime or a unique product of primes, which is why prime factorisation is sometimes called the 'DNA' of a number.
These ideas drive the simplification of fractions (using the greatest common factor) and adding fractions with unlike denominators (using the least common multiple), so mastering them pays off immediately in later topics. Divisibility rules (a number is divisible by 3 if its digits add to a multiple of 3) are a fast way to test factors.
Questions parents ask
Is 1 a prime number?
No. A prime has exactly two different factors, and 1 has only one.
What is the difference between GCF and LCM?
The greatest common factor is the largest number that divides two numbers exactly; the least common multiple is the smallest number that both numbers divide into.
Is 2 the only even prime?
Yes. Every other even number is divisible by 2, so it has at least three factors.
