Operations & Algebraic Thinking
GradesGrade 4Operations & Algebraic ThinkingFactors, Prime & Composite Numbers

Factors, Prime & Composite Numbers

🧠 Operations & Algebraic Thinking
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Factors, Prime & Composite Numbers

Every whole number can be described by its factor pairs — and some numbers are extra special!

A FACTOR is a number that divides evenly into another number. Every number has at least one FACTOR PAIR: 1 and itself. A PRIME number has exactly two factors: 1 and itself. A COMPOSITE number has more than two factors.

🔍Factor pairs of 12
Ask: what pairs multiply to give 12?
1 × 12 = 12
2 × 6  = 12
3 × 4  = 12

Factors of 12: 1, 2, 3, 4, 6, 12
12 has 6 factors → it is COMPOSITE.

Prime (exactly 2 factors)

2: factors are 1 and 23: factors are 1 and 35: factors are 1 and 57, 11, 13, 17, 19 …

Composite (more than 2 factors)

4: factors are 1, 2, 46: factors are 1, 2, 3, 69: factors are 1, 3, 910, 12, 15, 16 …

1 is NEITHER prime nor composite — it has only one factor (itself)!

How to find all factor pairs of a number n:

1Start with the pair: 1 × n
2Try 2: does it divide n evenly? If yes, write 2 × (n÷2)
3Try 3, then 4, and so on …
4Stop when your test factor reaches or passes √n (the factors start repeating)
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2 is the ONLY even prime number. All other even numbers are composite (divisible by 2).

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Remember This!

Quick divisibility shortcuts: divisible by 2 if ends in 0,2,4,6,8; by 3 if digit sum is divisible by 3; by 5 if ends in 0 or 5; by 10 if ends in 0.

✏️ Try It!

Which of the following numbers is PRIME?

Practice with CalcVerse
🔍Factors, GCF & LCM
Take Quiz 📝 — 25 Questions