MYP 3 Mathematics · Number

Discount and tax

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What Is Discount?

When businesses want to attract customers or clear old stock, they often reduce the price of an item below its original tag. This reduction is called a discount.

Marked Price

The original price shown on the price tag of an item before any discount is applied.

Discount

The amount of money by which the marked price is reduced. It represents a percentage decrease on the original price.

Selling Price

The actual price a customer pays after the discount has been applied.

The key relationship is:

Example

Simple Discount Example

A dishwasher has a marked price of 120 discount is offered. Find the sale price.

\text{Selling Price} = \\$495 - \\$120 = \\$375

The customer pays $375.

Discount as a Percentage

Most of the time, discounts are expressed as a percentage of the marked price rather than a fixed dollar amount. This makes it easy to apply the same deal to items of different prices.

There are two methods to calculate the selling price after a percentage discount:

Method 1 — Find the discount amount, then subtract:

  1. Convert the percentage to a decimal and multiply by the marked price to find the discount amount.
  2. Subtract the discount from the marked price.

Method 2 — Multiplier method (quicker):
If the discount is %, then the customer pays % of the marked price.

Example

Percentage Discount — Both Methods

A video projector has a marked price of $1060. A 22% discount is offered. Find the selling price.

Method 1:

  • Discount = 22% of 0.22 \times \233.20$
  • Selling price = 1060 - \826.80$

Method 2 (Multiplier):

  • Customer pays of the marked price.
  • Selling price = 1060 = \

Both methods give the same answer: $826.80.

Exam Tip

The multiplier method is faster and less prone to arithmetic errors — especially useful under timed conditions. Always ask: "What percentage does the customer actually pay?"

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