100% is the change from 10 to 20
Calculation steps:
[( 20 - 10 ) ÷ 10] x 100 = 100%
Formula
Percentage change = [(20 - 10) / 10] x 100
Subtract the new number by the original number
20 - 10 = 10
10 ÷ 10 = 1
1 x 100 = 100%
Example