UPSC Prelims 2020 CSAT Paper II · Q50 / 80 Basic Numeracy easy

What is the largest number among the following?

  1. (a) (1/2)⁻⁶
  2. (b) (1/4)⁻³
  3. (c) (1/3)⁻⁴ ✓ UPSC's answer
  4. (d) (1/6)⁻²

Why the answer is (c)

• A negative power of a fraction inverts it: (1/k)⁻ⁿ = kⁿ.

• (a) 2⁶ = 64; (b) 4³ = 64; (c) 3⁴ = 81; (d) 6² = 36.

• The largest is 81.

• Hence option (c).

Why the other options are wrong

(a) (1/2)⁻⁶
(1/2)⁻⁶ = 2⁶ = 64, which is less than 81.
(b) (1/4)⁻³
(1/4)⁻³ = 4³ = 64, which is less than 81.
(d) (1/6)⁻²
(1/6)⁻² = 6² = 36, the smallest of the four.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2020, held on 4 October 2020. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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