100% is the change from 25 to 50
Calculation steps:
[( 50 - 25 ) ÷ 25] x 100 = 100%
Formula
Percentage change = [(50 - 25) / 25] x 100
Subtract the new number by the original number
50 - 25 = 25
25 ÷ 25 = 1
1 x 100 = 100%
Example