Factors, multiples, and primes (age 9+)
Solve problems involving multiplication and division using knowledge of factors, multiples, squares, and cubes
What a learner can do afterwards
- Is 156 a multiple of 6? Explain how you know
- Find two square numbers that add to make 100
- Use factor pairs to simplify 24 × 25 as 6 × (4 × 25) = 6 × 100 = 600
The lesson
You already know your factors, multiples, squares, and cubes. Now you get to use them as tools. They help you check big numbers fast and turn hard multiplication into easy steps.
Is 156 a multiple of 6? A multiple of 6 must be a multiple of 2 and a multiple of 3. 156 is even, so it passes the first test. Add its digits: 1 + 5 + 6 = 12, and 12 is a multiple of 3. 156 passes both tests, so it is a multiple of 6.
Find two square numbers that add to make 100. Try 36 (which is 6 × 6) and 64 (which is 8 × 8). 36 + 64 = 100.
When a problem looks hard, look inside it for a shortcut: a factor pair, a multiple you know, or a square you remember. Break the number apart, solve the easy pieces, then put them back together.
Factors, multiples, and squares are shortcuts: use them to break hard problems into easy steps.
Watch it
Where it sits
This opens up
Nothing builds on it yet.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.