Percent Proportion/Equation

A percent is a ratio expressed as a fraction of 100. It represents a part of a whole.

To calculate the percent of a number, multiply the number by the percent (in decimal form). For example, to find 30% of 20, calculate 20 * 0.30 = 6.

Percent Change = ((New Value - Old Value) / Old Value) * 100.

Percent Increase = ((60 - 50) / 50) * 100 = 20%.

Percent Decrease = ((80 - 60) / 80) * 100 = 25%.

Finding the percent of a total means determining what portion of the total amount a specific part represents.

To express a percent as a decimal, divide the percent by 100. For example, 25% as a decimal is 0.25.

Fractions can be converted to percents by multiplying the fraction by 100. For example, 1/4 = 0.25 = 25%.

To find the original price after a discount, divide the sale price by (1 - discount rate). For example, if an item is $30 after a 25% discount, the original price is $30 / (1 - 0.25) = $40.

A proportion is an equation that states that two ratios are equal. For example, 1/2 = 2/4.