-23.9% is the change from 841 to 640
Calculation steps:
[( 640 - 841 ) ÷ 841] x 100 = -23.9%
Formula
Percentage change = [(640 - 841) / 841] x 100
Subtract the new number by the original number
640 - 841 = -201
-201 ÷ 841 = -0.2390011890606421
-0.2390011890606421 x 100 = -23.9%