-92.06% is the change from 642 to 51
Calculation steps:
[( 51 - 642 ) ÷ 642] x 100 = -92.06%
Formula
Percentage change = [(51 - 642) / 642] x 100
Subtract the new number by the original number
51 - 642 = -591
-591 ÷ 642 = -0.9205607476635514
-0.9205607476635514 x 100 = -92.06%