CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
If log₁₀ 2 = 0.3010, then the number of digits in 2^40 is:
2^40 has 13 digits. Its common logarithm is 40 × 0.3010 = 12.04, whose characteristic is 12, and the number of digits equals the characteristic plus one, giving 13.
- A12Correct
- B13
- C11
- D14
Explanation
log 2^40 = 40 × 0.3010 = 12.04. The characteristic is 12, so the number has 12 + 1 = 13 digits. Option 12 is wrong because it takes the characteristic as the digit count without adding 1.
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