What is 100 decreased by 20%?

100 decreased by 20% is 80. Calculate 20% of 100 = 20, then subtract that from 100: 100 − 20 = 80.

How do you calculate a percentage decrease?

Multiply the original value by the percentage and divide by 100 to get the change amount. Then subtract it from the original. For 20% decrease of 100: 100 × 0.2 = 20, then 100 − 20 = 80.

Quick Answer

20% Decrease of 100

100 − 20 = 80

How to Calculate 20% Decrease of 100

To find a percentage decrease, first calculate the change amount, then subtract it from the original value.

Step 1 — Find the change100 × 0.2 = 20

Step 2 — Subtract the change100 − 20 = 80

Answer20% decrease of 100 = 80

Alternatively: 100 × (1 − 0.2) = 100 × 0.8 = 80.

Other Percentage Decreases of 100

Change %	Base	Result
5%	100	95
10%	100	90
15%	100	85
20% ← you are here	100	80
25%	100	75
30%	100	70
40%	100	60
50%	100	50
75%	100	25
100%	100	0

Looking for the opposite? 20% increase of 100

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