# Comparing Quantities

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A ratio represents a relation that describes the comparison by division of two quantities of same kind and in the same unit.

A percentage is a way of expressing a number as a fraction of 100. ‘Per cent’ means "per hundred".

Percentage is denoted by using the percent sign, "%".

The percent of a quantity increases or decreases from its original amount is called the percent of change.

Discount is a reduction given on marked price.

Discount = Marked Price – Sale Price.

Discount can be calculated when discount percentage is given.

Discount = Discount % of Marked Price
Additional expenses made after buying an article are included in the cost price and are known as overhead expenses.

C.P. = Buying price + Overhead expenses
Whenever the Selling Price is greater than the Cost Price, we earn Profit.
If the Cost Price is greater than the Selling Price, we incur Loss.

The government charges a tax on the sale of an item. This is called ‘Sales Tax’.

Compound interest is the interest calculated on previous year’s amount.

Compound Interest = Amount – Principal
Amount is calculated as:
Amount = P × {1+(r/100)}n
Where P = Principal, R = Rate of interest, n = time period (in years)
If the cost of a machine depreciates at r% p.a. then its value after n years is given as
Cost after n years (A) = P {1 – (r/100)}n
Keywords: Value Added Tax (VAT), Simple interest

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