Basic Calculator

This is a straightforward four-function calculator for everyday arithmetic — addition, subtraction, multiplication, and division, with parentheses for grouping — without the trigonometric or logarithmic functions of a scientific calculator.

Mechanical calculating devices go back centuries: the abacus was in everyday use in Mesopotamia and China thousands of years ago, and Blaise Pascal built one of the first mechanical adding machines, the Pascaline, in 1642 to help his father with tax calculations. Electronic calculators didn't become small and affordable enough for everyday use until the 1970s, when advances in integrated circuits shrank what had once been room-sized computing equipment down to a device that fits in a pocket.

The order in which a calculator evaluates an expression — multiplication and division before addition and subtraction, with parentheses evaluated first — is usually remembered by the acronym PEMDAS (or BODMAS). This convention was standardized in math textbooks in the early 1900s specifically to remove ambiguity: without an agreed order, an expression like 4 + 6 × 2 could reasonably be read two different ways and produce two different, both seemingly "correct," answers. For functions like sine, logarithms, and exponents that go beyond core arithmetic, see the Scientific Calculator.

Each button builds up an expression exactly as you'd write it on paper, including parentheses for grouping operations. Pressing = evaluates the full expression using standard order of operations (multiplication and division before addition and subtraction).

Order of operations matters because arithmetic expressions with more than one operation are genuinely ambiguous without an agreed rule: 4 + 6 × 2 could mean "add 4 and 6, then multiply by 2" (20) or "multiply 6 by 2, then add 4" (16) depending on which operation is done first. Standard order of operations always resolves it the second way, and parentheses let you deliberately override that order whenever you need a specific part of the expression evaluated first.

The result reflects the exact evaluation of your typed expression using standard order of operations. An "Error" result means the expression was incomplete or invalid — check for unmatched parentheses or a missing number between operators.

Because the calculator evaluates your entire typed expression at once rather than step by step as you type, the result reflects standard order of operations across the whole expression — similar to typing a full formula into a spreadsheet cell and pressing enter, rather than pressing = after every single operation.