Divisibility Rules Explained with Examples | 20 MCQs for Competitive Exams (Beginner to Expert)
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Divisibility Rules Explained with Examples | 20 MCQs for Competitive Exams (Beginner to Expert)

⭐ Divisibility Rules (Detailed Explanation)

Divisibility rules help you quickly determine whether a number is divisible by another without performing full division. These rules are extremely useful in competitive exams for speed and accuracy.

1. Divisibility by 2

A number is divisible by 2 if its last digit is even (0, 2, 4, 6, 8).

Example:

246 → last digit 6 → divisible by 2.

2. Divisibility by 3

A number is divisible by 3 if the sum of its digits is divisible by 3.

Example:

372 → 3+7+2=12 (divisible by 3) → divisible by 3.

3. Divisibility by 4

A number is divisible by 4 if the last two digits form a number divisible by 4.

Example:

516 → last two digits 16 → divisible by 4 → yes.

4. Divisibility by 5

A number is divisible by 5 if its last digit is 0 or 5

Example:

475 → ends with 5 → yes.

5. Divisibility by 6

A number is divisible by 6 if it is divisible by both 2 and 3.

Example:

234 → even & sum=2+3+4=9 divisible by 3 → yes.

6. Divisibility by 7

A number is divisible by 7 using:

  • Double the last digit.
  • Subtract it from the remaining number.
  • If the result is divisible by 7 → original number is divisible.

Example: 203 → 20 – (2×3)=20–6=14 → divisible.

Example:

266 → 26 – (2×6)=26−12=14 → divisible → yes.

7. Divisibility by 8

A number is divisible by 8 if the last 3 digits form a number divisible by 8.

Example:

1032 → last three digits 032 = 32; 32 not divisible by 8 → no.

8. Divisibility by 9

A number is divisible by 9 if sum of digits is divisible by 9.

Example:

693 → 6+9+3=18 (divisible by 9) → yes.

9. Divisibility by 10

A number is divisible by 10 if its last digit is 0.

Example:

980 → ends with 0 → yes.

10. Divisibility by 11

A number is divisible by 11 if:

  • Find the alternating sum of digits.
  • If result is 0 or divisible by 11 → number divisible.

Example: 121 → (1 + 1) – 2 = 0 → divisible.

Example:

583 → (5+3) – 8 = 0 → divisible by 11.

MCQ's For Exam

Q.1. Which of the following is divisible by 2?

  1. 135
  2. 247
  3. 328
  4. 519

3) 328

📝Explanation: A number is divisible by 2 if its last digit is even (0,2,4,6,8). Option 328 ends with 8, so it is even and divisible by 2. The other choices end with odd digits (5,7,9), so they fail the divisibility-by-2 test and are not divisible by 2.

Q.2. Which number is divisible by 3?

  1. 142
  2. 357
  3. 412
  4. 100

2) 357

📝 Description: A number is divisible by 3 if the sum of its digits is divisible by 3. For 357, 3 + 5 + 7 = 15, and 15 ÷ 3 = 5 (no remainder), so 357 is divisible by 3. The other options have digit sums 7, 7, and 1 respectively, none divisible by 3.

Q.3. Which number is divisible by 4?

  1. 523
  2. 812
  3. 907
  4. 331

2) 812

📝 Description: A number is divisible by 4 when its last two digits form a number divisible by 4. For 812, the last two digits are 12, and 12 ÷ 4 = 3 (exact). Thus 812 is divisible by 4. The other options end with 23, 07, and 31, which are not divisible by 4.

Q.4. Which number is divisible by 5?

  1. 287
  2. 340
  3. 912
  4. 999

2) 340

📝 Description: A number is divisible by 5 only if it ends with 0 or 5. Among the options, 340 ends with 0, making it divisible by 5. All other numbers end with different digits (7, 2, 9), so they do not satisfy the divisibility rule for 5.

Q.5. Which of these is divisible by both 2 and 3?

  1. 114
  2. 115
  3. 117
  4. 119

1) 114

📝 Description: A number divisible by 6 must also be divisible by 2 (even number) and 3 (digit sum divisible by 3). 114 is even and its digit sum = 1+1+4 = 6, which is divisible by 3. Hence it satisfies both rules. Others fail the divisibility test for 2 or 3.

Q.6. Which of the following is divisible by 7?

  1. 84
  2. 95
  3. 140
  4. Both A & C

4) Both A & C

📝 Description: Using the divisibility rule for 7, subtract twice the last digit from the remaining number.

  • 84 → 8 – (2×4)=8−8=0 → divisible

  • 140 → 14 – (2×0)=14 → divisible
    Thus both 84 and 140 are divisible by 7, while 95 is not.

Q.7. Which number is divisible by 8?

  1. 7216
  2. 5012
  3. 3744
  4. All of these

4) All of these

📝 Description: A number is divisible by 8 if its last three digits form a number divisible by 8.

  • 216 → divisible by 8

  • 012 → 12 divisible by 8

  • 744 → divisible by 8
    Since all options satisfy the rule, the correct answer is All of these.

Q.8. Sum of digits divisible by 9 means the number is divisible by:

  1. 3
  2. 6
  3. 9
  4. 12

3) 9

📝 Description: The divisibility rule for 9 states that if the sum of digits of a number is divisible by 9, the entire number is divisible by 9. Although numbers divisible by 9 are also divisible by 3, option C is the correct and most specific rule being asked.

Q.9. Which number is divisible by 10?

  1. 450
  2. 453
  3. 459
  4. 465

1) 450

📝 Description: A number divisible by 10 must end with 0. Among the options, only 450 ends with 0. The remaining options end in 3, 9, and 5 respectively, which do not satisfy the rule for divisibility by 10.

Q.10. Which is divisible by 11?

  1. 121
  2. 242
  3. 374
  4. Both A & B

4) Both A & B

📝 Description: A number is divisible by 11 if the difference between the sum of digits in odd and even positions is 0 or divisible by 11.

  • 121 → (1+1)−2=0

  • 242 → (2+2)−4=0
    Both satisfy the rule, while 374 does not. Hence option D.

Q.11. A number divisible by both 4 and 6 is divisible by:

  1. 8
  2. 10
  3. 12
  4. 24

3) 12

📝 Description: To find the combined divisibility, we use the LCM of 4 and 6.
LCM(4, 6) = 12.
Therefore, any number divisible by both 4 and 6 must necessarily be divisible by 12, making option C correct.

Q.12. Which number is divisible by 3 but not by 9?

  1. 333
  2. 444
  3. 555
  4. 666

2) 444

📝 Description: A number divisible by 3 has digit sum divisible by 3; divisible by 9 requires digit sum divisible by 9.
444 → 4+4+4=12 → divisible by 3 but not by 9.
Other options have sums 9, 15, and 18 (all divisible by 9).

Q.13. If last 3 digits are 128, number is divisible by:

  1. 4
  2. 8
  3. 16
  4. All

2) 8

📝 Description: For divisibility by 8, check last three digits. 128 ÷ 8 = 16, so any number ending with 128 is divisible by 8.
It is also divisible by 4, but NOT always by 16. Hence the most accurate and safest answer is 8.

Q.14. The alternating sum rule applies to:

  1. 7
  2. 9
  3. 11
  4. 13

3) 11

📝 Description: A number is divisible by 11 if the alternating sum of its digits (odd position sum minus even position sum) is 0 or divisible by 11. No other number uses this rule, making 11 the unique correct answer.

Q.15. 4608 is divisible by which?

  1. 8
  2. 16
  3. 32
  4. All

4) All

📝 Description: Check last digits:

  • For 8 → last 3 digits 608 → divisible

  • For 16 → last 4 digits 4608 → divisible

  • For 32 → 4608 ÷ 32 = 144
    Since the number satisfies all three divisibility rules, the answer is All.

Q.16. Which is divisible by 9?

  1. 8991
  2. 9117
  3. 4356
  4. All

4) All

📝 Description: Apply digit-sum rule:

  • 8991 → 8+9+9+1 = 27 → divisible

  • 9117 → 9+1+1+7 = 18 → divisible

  • 4356 → 4+3+5+6 = 18 → divisible
    Since all have digit sums divisible by 9, all are divisible.

Q.17. Which number is divisible by 7?

  1. 231
  2. 350
  3. 448
  4. All

4) All

📝 Description: Using the divisibility test or known multiples:

  • 231 = 7 × 33

  • 350 = 7 × 50

  • 448 = 7 × 64
    Since all numbers are exact multiples of 7, option D is correct.

Q.18. If digit-sum = 27, number is divisible by:

  1. 9 only
  2. 3 only
  3. both 3 & 9
  4. neither

3) both 3 & 9

📝 Description: Digit-sum 27 is divisible by both 3 and 9. Therefore, any number with a digit sum of 27 is divisible by both 3 and 9. It cannot be divisible by only one of them, so option C is correct.

Q.19. 1001 is divisible by:

  1. 7
  2. 11
  3. 13
  4. All

4) All

📝 Description: 1001 is a special number because:
1001 = 7 × 11 × 13
Thus, it is divisible by all three numbers mentioned in the options. Therefore, the correct answer is All.

Q.20. Which number is divisible by 6?

  1. 202
  2. 222
  3. 232
  4. 242

2) 222

📝 Description: A number divisible by 6 must be divisible by both 2 and 3.
222 → even AND its digit sum = 2+2+2=6 (divisible by 3).
Other options either have digit sums not divisible by 3 or fail one of the rules.

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