Factors, Multiples & Primes
Year 7 🔢 Number Find factors, multiples, HCF, LCM and identify prime numbers.
🔍 Factors
A factor of a number divides into it exactly (no remainder).
Factors of 12: 1, 2, 3, 4, 6, 12
Check: 12 ÷ 1 = 12 ✓, 12 ÷ 2 = 6 ✓, 12 ÷ 3 = 4 ✓ ...
Check: 12 ÷ 1 = 12 ✓, 12 ÷ 2 = 6 ✓, 12 ÷ 3 = 4 ✓ ...
HCF
$$\text{HCF}(a,b) = \text{Highest Common Factor}$$📋 Multiples
A multiple of a number is in its times table.
Multiples of 4: 4, 8, 12, 16, 20, 24, ...
LCM(4,6) = 12 (lowest number in both lists)
LCM(4,6) = 12 (lowest number in both lists)
LCM
$$\text{LCM}(a,b) = \frac{a \times b}{\text{HCF}(a,b)}$$🔑 Prime Numbers
A prime number has exactly two factors: 1 and itself.
First primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 ... Note: 1 is NOT prime!
Prime Factorisation: 36 = 2² × 3² (write as product of prime factors)
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Interactive Demonstration — Factors, Multiples & Primes
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🔍 Factor & Prime Calculator