Turns out, those math classes you reluctantly took in college really do pay off.

The most profitable small-business industries today are all about the numbers, with accounting, tax and payroll services topping the list with an 18.4 percent net profit margin, according to a report by Sageworks, a financial information company.

Sageworks analyzed more than 16,000 businesses earning less than $10 million to determine which companies had the highest remaining revenues after all operating expenses, interest, taxes and preferred stock dividends had been deducted from them.

Here are the top 10 most profitable small-business industries and their net profit margins, as examined by Sageworks and reported by Entrepreneur:

1. Accounting and Tax Preparation; 18.4 percent
2. Company and Enterprise Management; 15.5 percent
3. Real Estate Agent and Broker Offices; 15.19 percent
4. Automotive Equipment Rental and Leasing; 14.55 percent
5. Legal Services; 14.48 percent
6. Dentist Offices; 14.41 percent
7. Electric Power Generation, Transmission and Distribution; 14.02 percent
8. Real Estate Lessors; 14.01 percent
9. Health Practitioner Offices; 13.30 percent
10. Physician Offices; 13.01 percent

For an expanded list, click here.