100% is the change from 251 to 502
Calculation steps:
[( 502 - 251 ) ÷ 251] x 100 = 100%
Formula
Percentage change = [(502 - 251) / 251] x 100
Subtract the new number by the original number
502 - 251 = 251
251 ÷ 251 = 1
1 x 100 = 100%
Example