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DSSSB PRT/TGT Number System Questions with Answers & Explanations

20 Number System questions from the Arithmetical & Numerical Ability section of DSSSB PRT/TGT, each with the correct answer and a worked explanation. Try each question first, then tap Show answer to check. When you're ready, take the timed chapter-wise test to see your all-India rank.

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Question 1

What is the LCM of 8 and 12?

  1. A48
  2. B96
  3. C28
  4. D24
Show answer
Answer: (D) 24 LCM = HCF × 2 × 3 = 24.
Question 2

What is the unit digit of 27^27?

  1. A3
  2. B5
  3. C8
  4. D1
Show answer
Answer: (A) 3 Unit digits of powers of 7 repeat in a cycle of 4; 27 mod 4 = 3, so the unit digit is 3.
Question 3

What is the remainder when 71286 is divided by 7?

  1. A5
  2. B2
  3. C3
  4. D1
Show answer
Answer: (A) 5 71286 = 7 × 10183 + 5.
Question 4

What is the square root of 729?

  1. A29
  2. B24
  3. C28
  4. D27
Show answer
Answer: (D) 27 27 × 27 = 729.
Question 5

What is the sum of the first 53 natural numbers?

  1. A1378
  2. B2809
  3. C1484
  4. D1431
Show answer
Answer: (D) 1431 Sum = n(n + 1)/2 = 53 × 54/2 = 1431.
Question 6

What is the sum of the first 49 natural numbers?

  1. A1225
  2. B1176
  3. C2401
  4. D1274
Show answer
Answer: (A) 1225 Sum = n(n + 1)/2 = 49 × 50/2 = 1225.
Question 7

What is the remainder when 70786 is divided by 17?

  1. A8
  2. B16
  3. C15
  4. D10
Show answer
Answer: (C) 15 70786 = 17 × 4163 + 15.
Question 8

What is the value of 93² − 32²?

  1. A3721
  2. B7686
  3. C7625
  4. D7525
Show answer
Answer: (C) 7625 a² − b² = (a + b)(a − b) = 125 × 61 = 7625.
Question 9

What is the square root of 289?

  1. A16
  2. B18
  3. C17
  4. D14
Show answer
Answer: (C) 17 17 × 17 = 289.
Question 10

What is the unit digit of 7^82?

  1. A3
  2. B9
  3. C5
  4. D6
Show answer
Answer: (B) 9 Unit digits of powers of 7 repeat in a cycle of 4; 82 mod 4 = 2, so the unit digit is 9.

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Question 11

What is the value of 72² − 11²?

  1. A3721
  2. B5063
  3. C5163
  4. D4963
Show answer
Answer: (B) 5063 a² − b² = (a + b)(a − b) = 83 × 61 = 5063.
Question 12

What is the sum of the first 52 natural numbers?

  1. A1430
  2. B1378
  3. C1326
  4. D2704
Show answer
Answer: (B) 1378 Sum = n(n + 1)/2 = 52 × 53/2 = 1378.
Question 13

What is the remainder when 40366 is divided by 13?

  1. A1
  2. B8
  3. C3
  4. D2
Show answer
Answer: (A) 1 40366 = 13 × 3105 + 1.
Question 14

What is the LCM of 24 and 40?

  1. A240
  2. B120
  3. C60
  4. D960
Show answer
Answer: (B) 120 LCM = HCF × 3 × 5 = 120.
Question 15

What is the square root of 4489?

  1. A67
  2. B64
  3. C68
  4. D69
Show answer
Answer: (A) 67 67 × 67 = 4489.
Question 16

What is the unit digit of 7^50?

  1. A6
  2. B8
  3. C2
  4. D9
Show answer
Answer: (D) 9 Unit digits of powers of 7 repeat in a cycle of 4; 50 mod 4 = 2, so the unit digit is 9.
Question 17

What is the value of 73² − 48²?

  1. A625
  2. B3025
  3. C2925
  4. D3050
Show answer
Answer: (B) 3025 a² − b² = (a + b)(a − b) = 121 × 25 = 3025.
Question 18

What is the sum of the first 34 natural numbers?

  1. A595
  2. B561
  3. C1156
  4. D629
Show answer
Answer: (A) 595 Sum = n(n + 1)/2 = 34 × 35/2 = 595.
Question 19

What is the remainder when 81941 is divided by 11?

  1. A8
  2. B5
  3. C3
  4. D2
Show answer
Answer: (D) 2 81941 = 11 × 7449 + 2.
Question 20

What is the square root of 961?

  1. A30
  2. B33
  3. C28
  4. D31
Show answer
Answer: (D) 31 31 × 31 = 961.

These are RankerClub practice questions written in the DSSSB PRT/TGT pattern. They are not official SSC/IBPS/RRB papers.

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