-21.48% is the change from 647 to 508
Calculation steps:
[( 508 - 647 ) ÷ 647] x 100 = -21.48%
Formula
Percentage change = [(508 - 647) / 647] x 100
Subtract the new number by the original number
508 - 647 = -139
-139 ÷ 647 = -0.21483771251931993
-0.21483771251931993 x 100 = -21.48%