100% is the change from 500 to 1000
Calculation steps:
[( 1000 - 500 ) ÷ 500] x 100 = 100%
Formula
Percentage change = [(1000 - 500) / 500] x 100
Subtract the new number by the original number
1000 - 500 = 500
500 ÷ 500 = 1
1 x 100 = 100%
Example