156% is the change from 250 to 640
Calculation steps:
[( 640 - 250 ) ÷ 250] x 100 = 156%
Formula
Percentage change = [(640 - 250) / 250] x 100
Subtract the new number by the original number
640 - 250 = 390
390 ÷ 250 = 1.56
1.56 x 100 = 156%
Example