-21.14% is the change from 842 to 664
Calculation steps:
[( 664 - 842 ) ÷ 842] x 100 = -21.14%
Formula
Percentage change = [(664 - 842) / 842] x 100
Subtract the new number by the original number
664 - 842 = -178
-178 ÷ 842 = -0.21140142517814728
-0.21140142517814728 x 100 = -21.14%