A number is first increased by 20%, then the resulting number is decreased by 20%. On the whole the original number is increased/decreased by :

1. 4% increased

2. 4% decreased

3. 2% increased

4. 2% decreased

Let the original number be 100.

After an increase of 20 %, it becomes = 100 + 20 % of 100

= $100 + \dfrac{20}{100} \times 100$

= $100 + \dfrac{2000}{100}$

= $100 + 20$

= 120

Now it is decreased by 20%, it becomes = 120 - 20 % of 120

= $120 - \dfrac{20}{100} \times 120$

= $120 - \dfrac{2,400}{100}$

= $120 - 24$

= 96

∴ Change on the whole = Final value - Initial value

= 96 - 100

= -4

Change on the whole is negative means change on the whole the number is decreasing.

∴ Percentage change = $\dfrac{\text{Change on the whole}}{\text{Initial value}} \times 100$ %

= $\dfrac{4}{100} \times 100$ %

= 4%

Hence, option 2 is the correct option.