Calculate with Basic
Percent is postfix: 10% becomes 0.1.
Safe allowlisted parser · No eval() · Angles in degrees
Formula and variables
- a, b
- the input numbers
- ○
- addition, subtraction, multiplication, or division
- c
- the calculated result
The calculator applies parentheses and powers first, then multiplication and division, then addition and subtraction.
Domain note: Division by zero is undefined. The percent key is postfix: 10% becomes 0.1 before the surrounding arithmetic is evaluated.
How to use this calculator
- 1
Enter a number or expression.
- 2
Choose arithmetic operators and parentheses as needed.
- 3
Press equals or Enter to calculate.
- 4
Use backspace to correct one character or AC to reset.
A complete example
Problem: Calculate 18 + 6 × 3.
Substitution: 18 + (6 × 3)
Result: 18 + 18 = 36
Multiplication is completed before addition, so the result is 36.
Understand the result
A finite decimal is shown with unnecessary floating-point noise removed. Very large or very small results use scientific notation.
Common mistakes
- Forgetting that multiplication and division run before addition and subtraction.
- Treating postfix percent as a relative-change key instead of dividing the preceding value by 100.
Frequently asked questions
How does the percentage key work?
It is a postfix operator: entering 25% converts 25 to 0.25 before the rest of the expression is evaluated.
Can I use the keyboard?
Yes. Use number keys, +, −, *, /, parentheses, Enter, Backspace, and Escape.
Why does division by zero show an error?
No real number multiplied by zero can recover a nonzero dividend, so division by zero is undefined.