Basic Calculator

Simple calculator for auction math and quick percent checks

AuctionMath's basic calculator evaluates arithmetic expressions with parentheses, decimals, and the standard order of operations: multiplication and division before addition and subtraction. Type in the expression field or use the keys. Press Enter or select equals to calculate; use C to clear and Back to remove the character before the cursor. Division by zero and incomplete expressions are shown as errors rather than silently treated as values.

Percent key examples

The percent key converts the number currently being entered to a percentage. For example, entering 200 + 10 and pressing % changes the expression to 200 + 20, because 10% of 200 is 20. Entering 200 x 10 and pressing % changes 10 to 0.1, so the result is 20. For a standalone 25, pressing % changes it to 0.25. These examples describe the percent key; a percent symbol typed as part of an expression is not an arithmetic operator.

History, privacy, and accuracy

Calculated expressions can be edited, recalculated, noted, reused, or deleted in the history panel. History is stored in this browser only and is not synced to an account; clearing browser site data removes it. Results use JavaScript number arithmetic and are displayed rounded to up to 10 decimal places, so verify currency calculations to the cent with an appropriate invoice tool before relying on them.