-97.7% is the change from 915 to 21
Calculation steps:
[( 21 - 915 ) ÷ 915] x 100 = -97.7%
Formula
Percentage change = [(21 - 915) / 915] x 100
Subtract the new number by the original number
21 - 915 = -894
-894 ÷ 915 = -0.9770491803278688
-0.9770491803278688 x 100 = -97.7%