90% is the change from 10 to 19
Calculation steps:
[( 19 - 10 ) ÷ 10] x 100 = 90%
Formula
Percentage change = [(19 - 10) / 10] x 100
Subtract the new number by the original number
19 - 10 = 9
9 ÷ 10 = 0.9
0.9 x 100 = 90%
Example