Profit margin is the percentage of revenue (income from sales) your business keeps as profit. It is one of the most common metrics used in accounting to determine your business's health.

We want to calculate the percentage of annual decline. First, we divide the most current revenue number by the beginning revenue number: $10 million divided by $15 million comes to 0.667.

Sales tax is a percentage of a retail price. To calculate it, convert the state sales tax percentage to a decimal, then multiply it by the retail price of the product or service.