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Divisibility Β· Topic 1 of 4

πŸ”’ Divisibility Rules

1 exam question type, fully solved

A divisibility rule is a quick test that tells you whether one number divides another, just by looking at the digits β€” no long division needed. Memorising these turns a slow sum into a five-second glance.

The rules worth memorising

β€’ By 2: the last digit is even (0, 2, 4, 6, 8).

β€’ By 5: the last digit is 0 or 5. Β  By 10: the last digit is 0.

β€’ By 4: the last two digits form a multiple of 4. Β  By 8: the last three digits form a multiple of 8.

β€’ By 3: the digit sum is a multiple of 3. Β  By 9: the digit sum is a multiple of 9.

β€’ By 6: divisible by both 2 and 3 together.

β€’ By 11: the difference (sum of digits at odd places) βˆ’ (sum at even places) is 0 or a multiple of 11.

β€’ By 7 (the standard trick): chop off the last digit, double it, and subtract it from the rest; repeat until you reach a small number β€” if that is a multiple of 7, so is the original. For : , and 63 is , so 672 is divisible by 7.

For a composite divisor (like 12, 33 or 132), split it into co-prime factors and apply each rule β€” more on that in the β€œMany Divisors” topic.

⚑Divisibility Rule CheckerType any number to instantly check all rules

5736 ends in 36, and , so 5736 is divisible by .

The digit sum of 4752 is , a multiple of 9, so 4752 is divisible by .

πŸ“Practice Questions

Q1Which of these is divisible by 4?

Q2Which of these is divisible by 9?

Q3A number ends in 0. It is definitely divisible by:

πŸ“š

Real exam questions β€” Divisibility Rules

1 question types Β· 5 solved examples from real SSC papers

Each divisor has a quick digit test, so you never actually divide. Run the easiest rule first to knock out wrong options.

How to solve this type
Each divisor has its own quick test. 2: last digit even. 5: last digit 0 or 5. 10: last digit 0. 4: last two digits divisible by 4. 8: last three digits divisible by 8. 3: digit sum divisible by 3. 9: digit sum divisible by 9. 11: the difference of the alternating digit sums is 0 or a multiple of 11. In a multiple-choice list, run the easiest rule first (last digit, then digit sum) to knock out wrong options fast.

Which of the following is divisible by 4: 7421, 5736, 8913, 3718?

A7421B5736C8913D3718

Which of the following is divisible by 5 but NOT by 2: 6135, 7200, 3750, 4820?

A6135B7200C3750D4820

What is the sum of the digits of 4752, and is 4752 divisible by 9?

A18, YesB17, NoC18, NoD19, Yes

How many of these are divisible by 10: 430, 725, 980, 1005, 1200?

A1B2C3D4

The sum of the three-digit numbers abc, bca and cab is always divisible by which number: 35, 31, 41 or 37?

A35B31C41D37