30.64% is the change from 643 to 840
Calculation steps:
[( 840 - 643 ) ÷ 643] x 100 = 30.64%
Formula
Percentage change = [(840 - 643) / 643] x 100
Subtract the new number by the original number
840 - 643 = 197
197 ÷ 643 = 0.30637636080870917
0.30637636080870917 x 100 = 30.64%