Question

One third of one half of one fifth of a number is $15$. Find the number

Answer 1

Let the required number be $x$.
Then, $\frac{1}{3}$ of $\frac{1}{2}$ of $\frac{1}{5}$ of $x=15$.
i.e. $\frac{1}{3}\times \frac{1}{2}\times \frac{1}{5}\times x=15$
$x=15\times 3\times 2\times 5$
$x=45\times 10=450$
Hence the required number is $450$.
Verification:
$LHS=\frac{1}{3}\times \frac{1}{2}\times \frac{1}{5}\times x$
$=\frac{1}{3}\times \frac{1}{2}\times \frac{1}{5}\times 450$
$=15=RHS$