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CTET 1 Mar 2026 Paper 1, Question 37

Topic: Numbers

Q37

The LCM of 21, 36, and 66 is not a multiple of :

  1. (1) 42
  2. (2) 28
  3. (3) 72Correct answer
  4. (4) 44

Solution.

CBSE answer: (3)

Answer: (3) 72

  1. 21=3×721 = 3 \times 7, 36=22×3236 = 2^2 \times 3^2, 66=2×3×1166 = 2 \times 3 \times 11.
  2. LCM =22×32×7×11=2772= 2^2 \times 3^2 \times 7 \times 11 = 2772.
  3. 42, 28 and 44 all divide 2772.
  4. 72=23×3272 = 2^3 \times 3^2 needs 232^3, but the LCM has only 222^2, so 2772 is not a multiple of 72.