Percent is a latin word which means per hundred or number out of 100. A percent can be represented as a fraction with a denominator of 100, or as a decimal.

For example, 65% = 65/100 = 0.65

### Concept of Percentage Increases

When a number is doubled, it is increased by 100%, not 200%, but the resulting number is 200% of the original number (and the original number is 50% of the resulting number).

For example, if the price of laptop computer increases from \$300 to \$600 over 10 years, the percent increase is 100% because the amount increased by \$300. \$600 is 200% of \$300 (and \$300 is 50% of \$600).

Similarly, when a number is tripled, it is increased by 200%, and the resulting number is 300% of the original number.

### Fractions and Percentages ### Percent Changes as Multipliers

Type 1: X% of a number

What is 40% of \$300? The multiplier in this case is the percent as a decimal. 40% as a decimal is 0.40, and \$300(0.40) = \$120, so \$120 is 40% of \$300.

Type 2: An X% increase or decrease

A person gets 20% increase in salary of \$300. What will be his new salary? In this case, the multiplier is 1 + (the percent as a decimal). Thus, \$300(1.20) = \$360, so that’s the amount person will get after 20% salary increase. In case of decrease, the multiplier will be 1 - (the percent as a decimal).