-34.71% is the change from 991 to 647
Calculation steps:
[( 647 - 991 ) ÷ 991] x 100 = -34.71%
Formula
Percentage change = [(647 - 991) / 991] x 100
Subtract the new number by the original number
647 - 991 = -344
-344 ÷ 991 = -0.34712411705348134
-0.34712411705348134 x 100 = -34.71%