-52.38% is the change from 21 to 10
Calculation steps:
[( 10 - 21 ) ÷ 21] x 100 = -52.38%
Formula
Percentage change = [(10 - 21) / 21] x 100
Subtract the new number by the original number
10 - 21 = -11
-11 ÷ 21 = -0.5238095238095238
-0.5238095238095238 x 100 = -52.38%