-18.7% is the change from 123 to 100
Calculation steps:
[( 100 - 123 ) ÷ 123] x 100 = -18.7%
Formula
Percentage change = [(100 - 123) / 123] x 100
Subtract the new number by the original number
100 - 123 = -23
-23 ÷ 123 = -0.18699186991869918
-0.18699186991869918 x 100 = -18.7%