-92.02% is the change from 639 to 51
Calculation steps:
[( 51 - 639 ) ÷ 639] x 100 = -92.02%
Formula
Percentage change = [(51 - 639) / 639] x 100
Subtract the new number by the original number
51 - 639 = -588
-588 ÷ 639 = -0.92018779342723
-0.92018779342723 x 100 = -92.02%