Factors, multiples and prime numbers
Find factors with rectangles, know the prime numbers, and work out the HCF and LCM. Read one step, play with it, then tap “I understand this”.
Factors: numbers that divide exactly
A factor of 12 is a number that divides into 12 with no remainder: 1, 2, 3, 4, 6 and 12. Factors come in pairs: 3 × 4 = 12.
Factor rectangles
Choose a number. Every rectangle you can build with all the blocks is a factor pair.
Prime and composite numbers
A prime number has exactly two factors: 1 and itself (2, 3, 5, 7, 11 …). A composite number has more than two. 1 is neither.
The number grid
Show the primes or the multiples of a number. Tap a number for its factors.
2 is the only even prime. Every other even number divides by 2.
A prime number has exactly two different factors: 1 and itself. 1 has only one factor, so it does not fit in the group. That keeps the rules neat: every number has just one set of prime factors, like 12 = 2 × 2 × 3.
Multiples and prime factors
Multiples of 3 are the 3 times table: 3, 6, 9, 12 … Every composite number can be written as a product of prime factors: 12 = 2 × 2 × 3.
Factors are smaller than (or equal to) the number; multiples are bigger than (or equal to) it. Do not mix them up.
HCF and LCM
The highest common factor (HCF) is the biggest number that divides into both numbers. The lowest common multiple (LCM) is the smallest number in both times tables.
Compare two numbers
Choose a and b. The yellow numbers are shared; the green one is the answer.
The HCF helps to simplify fractions; the LCM is the lowest common denominator.
With the HCF you simplify a fraction in one step. The LCM is the smallest denominator both fractions fit into when you add, so the numbers stay small.
Prime or not?
Prime or composite?
Choose for each number.
Correct: 0Check yourself
- Factors divide exactly into the number; they come in pairs.
- Prime number: exactly two factors (1 and itself). 1 is not prime.
- Multiples are the number’s times table: 3, 6, 9, 12 …
- HCF: highest common factor. LCM: lowest common multiple.
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 5 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
- Numbers9 pages · PDFPaperMemo
Ready for more? The Grade 7 prime factors quiz gives you new numbers every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Ask at the dinner table: “Can 24 sweets be shared equally between 5 children? And 6?” That is factors.
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 7 Maths. Always check your teacher’s notes and textbook too.