Question

A number is increased by 25% and then decreased by 20%. Find the percentage change in that number

Answer 1

Method 1:

Let the number be x.

First it is increased by 25%

∴ It becomes `x + 25/100 xx x = 125/100`

Secondary it is decreased by 20%

`125/100x - 20/100 xx 125/100x = 125/100x xx 80/100` = x

Now we get back x, therefore there is no change.

Hence percentage change in that number is 0%

Method 2:

To understand, let us assume that number is 100

So, first when we increase by 25%, we get

`100 + 25/100 xx 100` = 100 + 25 = 125

Now this 125 is decreased by 20%, we get

`125 - 20/100 xx 125` = 125 – 25 = 100

∴ We get back 100 ⇒ No change

Hence percentage change in that number is 0%