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JEE Main 2019 · 9 Apr · Shift II

JEE Main 2019 Physics question on Units and Measurements

The area of a square is 5.29 cm2^2. The area of 7 such squares taking into account the significant figures is
  1. A.
    37.030 cm2^2
  2. B.
    37.0 cm2^2
  3. C.
    37.03 cm2^2
  4. D.
    37 cm2^2
Show answer and solution

Correct option: C

Solution

5.29 cm² has 3 significant figures. Multiplying by the exact integer 7 gives 7 × 5.29 = 37.03 cm². Since 7 is an exact number (not a measured quantity), it doesn't limit significant figures, so the result retains 3 significant figures — but here 37.03 already has 4 significant figures with the last digit being meaningful because 7 is exact. The product 37.03 cm² correctly reflects all digits obtained from 7 × 5.29, keeping the same decimal precision (2 decimal places) as the original measurement, giving 37.03 cm².

[JEE Main 2019 · 9 Apr · Shift II]

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