CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
If log₁₀ 2 = 0.3010, the number of digits in 2⁴⁰ is:
2⁴⁰ has 13 digits. Its logarithm is 40 × 0.3010 = 12.04, whose characteristic is 12. The number of digits equals the characteristic plus one, so 13.
- A13Correct
- B12
- C14
- D11
Explanation
log₁₀(2⁴⁰) = 40 × 0.3010 = 12.04. The characteristic is 12, so the number has 12 + 1 = 13 digits. Choosing 12 mistakes the characteristic for the digit count.
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