-66.72% is the change from 646 to 215
Calculation steps:
[( 215 - 646 ) ÷ 646] x 100 = -66.72%
Formula
Percentage change = [(215 - 646) / 646] x 100
Subtract the new number by the original number
215 - 646 = -431
-431 ÷ 646 = -0.6671826625386997
-0.6671826625386997 x 100 = -66.72%