How to Use the Basic Calculator
Using the CalculatorAha basic calculator is simple. Click the number buttons to enter your first number, then press an operator — + (add), − (subtract), × (multiply) or ÷ (divide). Enter your second number and press = to instantly see your result.
You can chain calculations — after pressing equals, continue entering a new operator and number without clearing the display.
Special Buttons Explained
- AC (All Clear) — Resets everything to zero. Start a completely fresh calculation.
- +/− (Toggle Sign) — Switches the current number between positive and negative.
- % (Percent) — Converts the number to its percentage form. For example: 15 → 0.15.
- . (Decimal) — Adds a decimal point for numbers like 3.14 or 0.75.
- Backspace — Press on keyboard to remove the last digit entered.
Keyboard Shortcuts
You can operate the entire calculator from your keyboard:
- 0–9 — Enter digits
- + − * / — Arithmetic operators (use * for multiply, / for divide)
- Enter or = — Calculate the result
- Escape — Clear all
- Backspace — Delete last digit
Frequently Asked Questions
How do I calculate a percentage of a number? +
To find 20% of 150: enter 150, press ×, enter 20, press %, then press =. The result is 30. Alternatively enter 150 × 0.20 = for the same result.
Can I use this calculator on my phone? +
Yes — CalculatorAha.com is fully mobile-optimised with large tap-friendly buttons. Works perfectly on iPhone, Android, and any tablet.
Does the calculator save my history? +
Yes! Every calculation appears in the History section below the calculator. Click any item to recall it. Press Clear to erase history.
What is the difference between basic and scientific calculator? +
A basic calculator handles the four core operations: addition, subtraction, multiplication and division. A scientific calculator adds trigonometric functions, logarithms, exponents and more. For everyday calculations a basic calculator is all you need.
Is this calculator free? +
Completely free — forever. No account, no sign-up, no subscription required.
