-81% is the change from 642 to 122
Calculation steps:
[( 122 - 642 ) ÷ 642] x 100 = -81%
Formula
Percentage change = [(122 - 642) / 642] x 100
Subtract the new number by the original number
122 - 642 = -520
-520 ÷ 642 = -0.8099688473520249
-0.8099688473520249 x 100 = -81%