Grade 4 (+ Grade 5) Divisibility Rules

Divisibility Rules Explained

Steps

Divisible means no remainder: 24 ÷ 6 = 4 exactly.
2, 5, 10 — last digit: even → 2; ends in 0 or 5 → 5; ends in 0 → 10. Why: every ten is made of 2s, 5s and 10s.
3 and 9 — digit sum: 471 → 4 + 7 + 1 = 12 → divisible by 3. 3,456 → 18 → divisible by 9. Why: 10 = 9 + 1, 100 = 99 + 1.
4 — last two digits: 7,316 → 16 = 4 × 4 ✓. Why: 100 = 4 × 25.
6 — both 2 and 3: 534 is even and 5 + 3 + 4 = 12 ✓. Non-example: 328 (digit sum 13).
Use the rules for factor pairs (36: 1×36, 2×18, 3×12, 4×9, 6×6) and prime vs composite (51 = 3 × 17 is composite). 1 is neither.
Rhyme: “Check the end for 2, 5 and 10; add the digits for 3 and 9; last two digits for 4; 6 needs 2 and 3 — then you’re fine!”