A number is increased by 20% and then it is decreased by 20%. Find the net increase or decrease per cent.

Sure, let's solve the problem step by step.

Step 1: Let's assume the number is x.

Step 2: The number is increased by 20%. This means we need to find 20% of x and add it to x.

20% of x = (20/100) * x = 0.2x

So, the new number after the increase is x + 0.2x = 1.2x.

Step 3: The number is then decreased by 20%. This means we need to find 20% of 1.2x and subtract it from 1.2x.

20% of 1.2x = (20/100) * 1.2x = 0.24x

So, the final number after the decrease is 1.2x - 0.24x = 0.96x.

Step 4: To find the net increase or decrease percentage, we need to compare the final number (0.96x) with the original number (x).

Net increase or decrease percentage = ((final number - original number) / original number) * 100

= ((0.96x - x) / x) * 100

= (-0.04x / x) * 100

= -4%

Therefore, the net increase or decrease percentage is -4%.