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