-98% is the change from 850 to 17
Calculation steps:
[( 17 - 850 ) ÷ 850] x 100 = -98%
Formula
Percentage change = [(17 - 850) / 850] x 100
Subtract the new number by the original number
17 - 850 = -833
-833 ÷ 850 = -0.98
-0.98 x 100 = -98%
Example