Question

One-third of the square root of which number is $0.001$ ?

• A. 1
• B. 0.000009
• C. 0.003
• D. 0.009

Answer 1

The correct option is B 0.000009

Let the required number be $x$. Then
$\frac{1}{3}\times \sqrt{x}=0.001$

$\Rightarrow \sqrt{x}=0.001\times 3=0.003$
$\therefore x=(0.003{)}^2=0.000009$
Note that there are 3 decimal places in the number so there will be 6 decimal places in the square of he number.