Question

A number is increased by $20\%$ and the increased number is decreased by $20\%$. Find the net increase of decrease per cent.

Answer 1

Let the number be $100$.
Increase in the number $=20\%$
So, $20\%$ of $100=\frac{20}{100}\times 100$
$=20$
Thus, the increased number $=(100+20)=120$
Now, decrease in the number$=\left(20\%\text{of}120\right)$
$=\frac{20}{100}\times 120$
$=24$
New number$=(120-24)=96$
Net decrease $=(100-96)=4$
Net decrease percentage $=\frac{4}{100}times100=4$
Hence, the net decrease percentage is $4\%$.