Question

a number is increased by 20% and then decreased by 20% find the net increase or decrease in percentage

Answer 1

Suppose we take the number as 100
So, after increase the number becomes

number = 100  + 20/100 * 100
= 100 + 20 = 120
So, now to decrease the number 120 by 20%

number = 120 - 20/100 * 120
= 120 - 24
= 96

Now,
96 < 100 by 4.

So,  there is a net decrease of 4%.

Answer 2

Let the number = 100

When number is increased by 20%

Increased number = 100 x 20/100
= 20
= 120
When the number is decreased by 20%

Decreased number = increased number x 20%

= 120 x 20/100
= 24
= 120 - 24
= 96