Basic Arithmetic Calculator
A safe online calculator for everyday arithmetic with + − × ÷, parentheses, percentages and square roots, following order of operations.
Your inputs
Results
Result
122.5
✓Exact calculation — rounded only for display
What this calculator does
Type an expression or use the keypad. The calculator follows standard order of operations (brackets, powers, multiplication and division, then addition and subtraction).
Formula and method
Expressions are parsed by a grammar-based evaluator; % divides the preceding number by 100 and √ takes a square root. No code is ever executed.
Worked example
Calculated by this tool with its default inputs:
Inputs
- Expression: 12.5 × (4 + 6) − 20 ÷ 8
Results
- Result: 122.5
How to read the results
Results are rounded to 12 significant figures to hide binary floating-point noise such as 0.1 + 0.2 = 0.30000000000000004.
Assumptions and limitations
- Use the scientific calculator for trigonometry, logarithms and powers of e.
Questions
How is 200 × 15% evaluated?
15% becomes 0.15, so the result is 30.
Methodology and verification
- Result type
- Exact mathematical calculation (rounded only for display)
- Formula version
- 1.0
- Automated verification
- 7 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
- Editorial review
- Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.
Privacy
Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Inputs are added to a share link only if you choose to include them. Privacy policy