Basic Calculator
A simple online calculator for everyday addition, subtraction, multiplication, and division with a running calculation history
By Waqar Mushtaq · Last updated:
This basic calculator handles everyday addition, subtraction, multiplication, and division right in your browser — no app to install, no signup. Type in numbers, tap the operators, and each step is logged to a scrollable calculation history so you can trace back exactly how you got to a result.
How a basic calculator evaluates operations
Each operator is applied immediately, left to right
A basic (four-function) calculator evaluates left to right as you press keys, applying each operator to the running total immediately — it does not use operator precedence (PEMDAS/BODMAS) the way a scientific calculator or a written expression does.
For example, typing 2 + 3 × 4 gives 20 on a basic calculator, because it computes 2 + 3 = 5 first, then 5 × 4 = 20. A scientific calculator or expression evaluator would instead apply multiplication before addition and return 14 (3 × 4 = 12, then 2 + 12 = 14).
This left-to-right, no-precedence behavior is exactly how physical four-function calculators (and this tool) work, and it's a common source of confusion when comparing a basic calculator's answer to one from a formula or spreadsheet.
Division by zero is undefined, so the calculator shows an error instead of a number in that case.
Use Cases
Quick everyday math
Splitting a bill, checking a total at checkout, or adding up a grocery list — a basic calculator is faster than opening a spreadsheet for simple arithmetic.
Checking work step by step
The calculation history logs every operation as you go, so you can double-check each intermediate step instead of just trusting a final number.
Percentage adjustments
The % key converts the current entry to its percentage value (dividing by 100), useful for quickly figuring out a tip, discount, or tax amount before adding or subtracting it.
Frequently Asked Questions
Why does this calculator give a different answer than typing the same numbers into a formula?
A basic calculator evaluates strictly left to right as you press each key — it does not follow order of operations (PEMDAS). 2 + 3 × 4 evaluates as (2 + 3) × 4 = 20 here, while a formula or scientific calculator applies multiplication first and gets 2 + (3 × 4) = 14. Neither is "wrong" — they follow different, well-defined evaluation rules.
What happens if I divide by zero?
Division by zero is mathematically undefined, so the calculator displays "Error" instead of a number. Press C to clear and start a new calculation.
Can I see my previous calculations?
Yes — every operation you complete is added to the Calculation History list below the keypad, most recent first, so you can scroll back through your session.
Methodology
The formula above is implemented as a standalone module covered by unit tests, so its worked examples are re-checked on every change to the site. It is verified against the authoritative sources listed below.
Maintained by Waqar Mushtaq. Spotted a result that looks wrong? Report it and it becomes a failing test.