To decrease an amount by 19% multiply by

Think of the original amount as 100%

If we want 100% of something we multiply by 1

To get from 100% to 1, we divide the percentage by 100

Decrease 100% by 19%

100% - 19% = 81%

Then to get the multiplier, divide by 100

81% / 100 = 0.81

To decrease by 19%, multiply by 0.81