As we saw in a previous post, adding a percentage is a multiplication.

For instance, adding 20% to a tax free price, to obtain the VAT included price, is multiplying by (1+20/100)=1.20=1.2.

But what I would like you to know today, is that subtracting a percentage is NOT a division, but a multiplication as well!

For instance, a coupon of 30% on a price of $100 is subtracting 30% of $100, that is (30/10)*$100=$30. The reduced price is $100-$30=$70, that is 0.70 times $100.

Another way to...