DIV007 · Factors, multiples & divisibility · Classes 4–7
Divisibility by 3
A number is divisible by 3 when the sum of its digits is divisible by 3.
4+7+1 = 12Divisibility by 3
📐 Formula
n divisible by 3 ⇔ digit sum divisible by 3
✏️ Worked example
471: 4 + 7 + 1 = 12, which is divisible by 3, so 471 ÷ 3 = 157.
🌍 Where it is used
Quick checks when sharing among 3 people.
❓ Quick check
Which is divisible by 3?
🏋️ Practice
EasyIs 81 divisible by 3?
Answer: Yes (8 + 1 = 9)
MediumIs 1,001 divisible by 3?
Answer: No (digit sum 2)
ChallengeFill the blank so 5_2 is divisible by 3 (smallest digit).
Answer: 2 (522)