Using percentages for expressing discounts and comparing prices

Question 2

Calculate the sale price of each of the following kittens without using a calculator.
Which kitten is the best buy?

Original price	$25	$60	$40
Discount	10%	50%	25%

Solution

10% = \(\dfrac{10}{100}\) = \(\dfrac{1}{10}\)	(To calculate 10% of an amount, divide it by 10.)
25% = \(\dfrac{25}{100}\) = \(\dfrac{1}{4}\)	(To calculate 25% of an amount, divide it by 4.)
50% = \(\dfrac{50}{100}\) = \(\dfrac{1}{2}\)	(To calculate 50% of an amount, divide it by 2.)

Sale prices

First kitten	= $25 − \(\dfrac{$25}{10}\)	(Subtract one-tenth of the original.)
	= $25 − $2.50
	= $22.50.
Second kitten	= $60 − \(\dfrac{$60}{2}\)	(Subtract one-half of the original.)
	= $60 − $30
	= $30.
Third kitten	= $40 − \(\dfrac{$40}{4}\)	(Subtract one-quarter of the original.)
	= $40 − $10
	= $30.

Best buy

The first kitten is the cheapest. However, you might want to consider other factors before buying it; for example the health of the kitten and your personal preference for things like colour and breed.

Method 2

Question 3