-21.15% is the change from 643 to 507
Calculation steps:
[( 507 - 643 ) ÷ 643] x 100 = -21.15%
Formula
Percentage change = [(507 - 643) / 643] x 100
Subtract the new number by the original number
507 - 643 = -136
-136 ÷ 643 = -0.2115085536547434
-0.2115085536547434 x 100 = -21.15%