If you want to increase something by 3%, you would ADD 100% to it, so: 3% + 100% = 103% Then you divide it by 100 to turn it into a decimal, so: 103% / 100 = 1.03 So to increase by 3%, the multiplier would be 1.03
If you wanted to decrease by 3%, you would SUBTRACT 100% from 3%, so: 100% - 3% = 97% And then you would divide 97% by 100 to turn it into a decimal (multiplier), so: 97% / 100 = 0.97 So to decrease by 3%, the multiplier would be 0.97
