ABC26GN2098 · Logarithms

Subject: General Aptitude · Chapter: Logarithms · Exam: · Marks: · Difficulty:

If $\log 2=0.30103, \log 3=0.47712$, then the number of digits in $6^{20}$ is
(a)15
(b)16
(c)17
(d)18
Answer
Answer (as printed): B
Explanation
$$\begin{aligned} \log 6^{20} & =20 \log (2 \times 3)=20(\log 2+\log 3) \\ & =20(0.30103+0.47712) \\ & =20 \times 0.77815=15.563 \end{aligned}$$ ∴ Characteristic $=15$. Hence, the number of digits in $6^{20}=16$.

Explanation as extracted from the printed page; notation may be imperfect.

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