820% is the change from 70 to 644
Calculation steps:
[( 644 - 70 ) ÷ 70] x 100 = 820%
Formula
Percentage change = [(644 - 70) / 70] x 100
Subtract the new number by the original number
644 - 70 = 574
574 ÷ 70 = 8.2
8.2 x 100 = 820%
Example