How to Calculate a Tip
Learn how to calculate a tip quickly using a simple percentage formula. See how to calculate the tip amount, total bill, split the bill between multiple people, and handle common tip percentages such as 15%, 18%, 20%, and 25%.
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Money & Math
Understand percentages, loans and mortgages with clear, worked examples.
How to Calculate Percentage Change: Formula, Examples, and Calculator
Learn how to calculate percentage change between two values using a simple formula. See how to work out percentage increases and decreases, understand the difference between percentage change and percentage difference, and check your result with the free ToolCMB Percentage Calculator.
How Compound Interest Works: Formula, Examples, and Why Time Matters
Compound interest lets your money earn interest on both the original amount and the interest already accumulated. Learn how compound interest works, see the formula with simple examples, and understand how interest rates, compounding frequency, regular deposits, and time affect your savings.
How Mortgage Interest Is Calculated: A Simple Guide to Mortgage Interest
Mortgage interest is calculated from your outstanding loan balance and interest rate, so the amount of interest you pay usually decreases as you pay down the principal. Learn how mortgage interest is calculated, how amortization changes the split between interest and principal, and how to estimate your total interest with a mortgage calculator.
How to Calculate Your Monthly Mortgage Payment
The mortgage formula in plain English, a worked example and the four numbers that change your payment the most.