About the Basic Calculator
A basic calculator performs the four fundamental arithmetic operations — addition, subtraction, multiplication, and division — on two numbers. It is the tool for a quick, reliable answer when you want the number without the interface of a scientific calculator.
The formula
a + b, a − b, a × b, a ÷ bThe two operands are the numbers you enter. Division requires a non-zero divisor, since dividing by zero has no defined result.
How to use this calculator
- 1Enter your Number 1. The field starts at
10, which you can overwrite. - 2Enter your Number 2. The field starts at
5, which you can overwrite. - 3Read the result straight away — it recalculates as you type, so there is no button to press. Use Share to copy a link that reopens the page with your exact numbers filled in.
Worked example
| Input | Value |
|---|---|
| Number 1 | 10 |
| Number 2 | 5 |
Result
Addition: 15
Subtraction: 5
Multiplication: 50
Division: 2
Those are the values the page loads with, so you can reproduce this result yourself and then change one field at a time to see what drives the outcome.
Understanding your result
Arithmetic on two numbers is unambiguous, but chains of operations are not, which is where order of operations comes in. The convention is parentheses, then exponents, then multiplication and division left to right, then addition and subtraction left to right. Without it, 2 + 3 × 4 could mean 20 or 14; the convention makes it 14.
Decimal arithmetic on a computer is not always exact, because values such as 0.1 have no finite binary representation. This is why 0.1 + 0.2 can display as 0.30000000000000004 in some contexts. Results here are rounded for display, which hides the artefact, but it is worth knowing about when precision matters.
Things worth knowing
- Division by zero is undefined, not infinite, and any calculator that returns a number for it is wrong.
- Multiplying two negatives gives a positive; multiplying a negative and a positive gives a negative.
- For money, round only at the final step. Rounding intermediate results compounds the error.
- Estimating the answer first catches typos. If you expect roughly 50 and see 500, you have a misplaced decimal.
- Subtraction and division are not commutative — order changes the answer, unlike addition and multiplication.
Frequently asked questions
What is the correct order of operations?+
Parentheses first, then exponents, then multiplication and division working left to right, then addition and subtraction working left to right. It is often remembered as PEMDAS or BODMAS.
Why can I not divide by zero?+
Because no number multiplied by zero gives a non-zero result, so the question has no answer. It is undefined rather than infinite, and treating it as infinity leads to contradictions.
Why do decimals sometimes produce odd results?+
Computers store decimals in binary, and fractions like 0.1 cannot be represented exactly, so tiny rounding errors accumulate. Displayed results are rounded, which normally hides it.
Does 2 + 3 × 4 equal 20 or 14?+
Fourteen. Multiplication takes precedence over addition, so 3 × 4 is evaluated first. Writing (2 + 3) × 4 is how you would get 20.