Question

If a measured quantity has $n$ significant figures, the reliable digits in it are :

• A. n
• B. n-1
• C. 2n
• D. n/2

Answer 1

The correct option is B n-1

A measured quantity containing $n$ significant figures has $n-1$ reliable digits.

For example: The quantity $a=1.2673$ has $5$ significant figures but it contains only $4$ reliable digits i.e $1.267$ only.

Because it can be a possiblity that the quantity was acually $a=1.26728$ and after rounding off, it becomes $1.2673$.

Hence the last digit i.e $3$ is uncertain.