-81.98% is the change from 172 to 31
Calculation steps:
[( 31 - 172 ) ÷ 172] x 100 = -81.98%
Formula
Percentage change = [(31 - 172) / 172] x 100
Subtract the new number by the original number
31 - 172 = -141
-141 ÷ 172 = -0.8197674418604651
-0.8197674418604651 x 100 = -81.98%