-12.1% is the change from 1000 to 879
Calculation steps:
[( 879 - 1000 ) ÷ 1000] x 100 = -12.1%
Formula
Percentage change = [(879 - 1000) / 1000] x 100
Subtract the new number by the original number
879 - 1000 = -121
-121 ÷ 1000 = -0.121
-0.121 x 100 = -12.1%