-50.7% is the change from 647 to 319
Calculation steps:
[( 319 - 647 ) ÷ 647] x 100 = -50.7%
Formula
Percentage change = [(319 - 647) / 647] x 100
Subtract the new number by the original number
319 - 647 = -328
-328 ÷ 647 = -0.5069551777434312
-0.5069551777434312 x 100 = -50.7%