100% is the change from 1 to 2
Calculation steps:
[( 2 - 1 ) ÷ 1] x 100 = 100%
Formula
Percentage change = [(2 - 1) / 1] x 100
Subtract the new number by the original number
2 - 1 = 1
1 ÷ 1 = 1
1 x 100 = 100%
Example