Discounts and mark-ups are the two most common commercial cases of percentage decrease and increase. In both, the starting price is multiplied by a single factor.

Definition — Discount and mark-up

A discount of p%p\% on a price P0P_0 leads to a new price P=P0(1p100).P = P_0\Bigl(1-\frac{p}{100}\Bigr). A mark-up of p%p\% is instead P=P0(1+p100).P = P_0\Bigl(1+\frac{p}{100}\Bigr).

Recognising in (1p100)\bigl(1-\frac{p}{100}\bigr) and (1+p100)\bigl(1+\frac{p}{100}\bigr) the multiplicative factors seen for decreases and increases lets us chain several operations simply by multiplying the factors together.

Topics: Percentages
Concepts: Mark-up · Discount
Methods: Discount percentage
Skills: Calculating · Using formulae