-1.57% is the change from 830 to 817
Calculation steps:
[( 817 - 830 ) ÷ 830] x 100 = -1.57%
Formula
Percentage change = [(817 - 830) / 830] x 100
Subtract the new number by the original number
817 - 830 = -13
-13 ÷ 830 = -0.01566265060240964
-0.01566265060240964 x 100 = -1.57%