-87.86% is the change from 420 to 51
Calculation steps:
[( 51 - 420 ) ÷ 420] x 100 = -87.86%
Formula
Percentage change = [(51 - 420) / 420] x 100
Subtract the new number by the original number
51 - 420 = -369
-369 ÷ 420 = -0.8785714285714286
-0.8785714285714286 x 100 = -87.86%