-19.78% is the change from 637 to 511
Calculation steps:
[( 511 - 637 ) ÷ 637] x 100 = -19.78%
Formula
Percentage change = [(511 - 637) / 637] x 100
Subtract the new number by the original number
511 - 637 = -126
-126 ÷ 637 = -0.1978021978021978
-0.1978021978021978 x 100 = -19.78%