100% is the change from 450 to 900
Calculation steps:
[( 900 - 450 ) ÷ 450] x 100 = 100%
Formula
Percentage change = [(900 - 450) / 450] x 100
Subtract the new number by the original number
900 - 450 = 450
450 ÷ 450 = 1
1 x 100 = 100%
Example