-4.17% is the change from 647 to 620
Calculation steps:
[( 620 - 647 ) ÷ 647] x 100 = -4.17%
Formula
Percentage change = [(620 - 647) / 647] x 100
Subtract the new number by the original number
620 - 647 = -27
-27 ÷ 647 = -0.04173106646058733
-0.04173106646058733 x 100 = -4.17%