-30.08% is the change from 921 to 644
Calculation steps:
[( 644 - 921 ) ÷ 921] x 100 = -30.08%
Formula
Percentage change = [(644 - 921) / 921] x 100
Subtract the new number by the original number
644 - 921 = -277
-277 ÷ 921 = -0.3007600434310532
-0.3007600434310532 x 100 = -30.08%