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CTET 7 Feb 2026 Paper 1, Question 33

Topic: Numbers

Q33

The sum of all the common factors of 36 and 48 (excluding 1) is

  1. (1) 26
  2. (2) 27Correct answer
  3. (3) 28
  4. (4) 29

Solution.

CBSE answer: (2)

Answer: (2) 27

  1. Common factors of two numbers are exactly the factors of their HCF.
  2. 36=22×3236 = 2^2 \times 3^2, 48=24×348 = 2^4 \times 3, so HCF =22×3=12= 2^2 \times 3 = 12.
  3. Factors of 12: 1, 2, 3, 4, 6, 12. Sum =28= 28.
  4. Leaving out 1: 28−1=2728 - 1 = 27.

Trap: 28 is the sum with 1 included; the question excludes 1.