Simple Math Calculator
A clean, fast calculator for everyday arithmetic — bills, discounts, tips, and the quick sums that don't need a full financial tool. Works with your mouse, your keyboard, or your thumb.
Works like a physical calculator: keys are evaluated in the order you press them, left to right. Type numbers on your keyboard, use + − × ÷ or * /, and Enter for equals.
History
0 calculations- Your calculations will appear here as you go.
Tap any past result to bring it back into the display.
How to Use This Calculator
Type a number, press an operator, type the next number, and press equals — the same sequence as any handheld calculator. There is nothing to install and nothing to type into a formula box: click the buttons, use your keyboard, or mix both in the same calculation.
- C clears the current entry back to zero.
- ⌫ deletes the last digit you typed, without losing the rest of the number.
- ± flips the sign of whatever is on screen, positive to negative or back.
- % converts the number on screen to a percentage — see the worked examples below for exactly what that does mid-calculation.
- Clear everything resets the calculator and wipes the history panel.
Press equals a second time with no new numbers entered and it repeats the last operation on the current result — handy for quickly running a number up in fixed steps.
Why "2 + 3 × 4" Gives 20 Here, Not 14
This is deliberate, and worth understanding before you rely on it. A scientific or algebraic
calculator applies order of operations (PEMDAS/BODMAS) — multiplication before addition —
so 2 + 3 × 4 evaluates to 14. This calculator, like the physical calculator on your
desk or phone, is a chained calculator: it evaluates strictly in the order you press the
keys. Enter 2 + 3 × 4 = here and it computes (2 + 3) × 4, giving
20.
Neither behaviour is "wrong" — they are two different, well-established calculator designs, and most handheld and phone calculators default to the chained model this tool uses. If a calculation has several operations and the order matters, enter it as separate steps, or force the order yourself by pressing equals after the part you want evaluated first.
Handy Everyday Calculations
The % key is more useful than it looks. Press it after + or − and
it converts the number on screen into that percentage of the value already entered — which
is exactly what a tip or a discount is.
Adding a tip
85 + 15 % = 12.75 → press = again → 97.75
On an $85 bill, press 8 5 + 1 5 % and the screen shows 12.75 — the tip amount
by itself. Press = and it becomes 97.75, the full bill with tip included.
Both numbers are useful, and now you have both without retyping anything.
Taking off a discount
60 − 20 % = 12 → press = again → 48
A $60 item at 20% off: 6 0 − 2 0 % shows 12, the amount you save. Press
= for 48, the price you actually pay.
Splitting a bill
126.40 ÷ 4 = 31.60
Total the bill, press ÷, enter the number of people, and press equals. Add a tip
first using the method above if you're splitting the total including tip.
Keyboard Shortcuts
| Key | Action |
|---|---|
| 0–9 | Enter digits |
| . | Decimal point |
| + − * / | Add, subtract, multiply, divide |
| Enter or = | Equals |
| Backspace | Delete last digit |
| Esc or C | Clear |
| % | Percent |
Frequently Asked Questions
Why doesn't this calculator follow order of operations?
It's built to match a physical or phone calculator rather than a scientific one — operations run in the order you press them, not by mathematical precedence. See "Why 2 + 3 × 4 gives 20 here" above for a full worked example of the difference.
How accurate are the results?
Calculations use standard double-precision arithmetic and are rounded to 12 significant digits to remove floating-point noise (so 0.1 + 0.2 correctly shows 0.3, not 0.30000000000000004). That's precise enough for any everyday, financial or shopping calculation.
What happens if I divide by zero?
The display shows "Error." Press C to clear it and start again — dividing by zero is undefined, not a bug.
Is my calculation history saved anywhere?
No. History lives only in your browser tab for the current session. Refresh the page or close the tab and it's gone — nothing is sent to a server or stored.
Can I use this on my phone?
Yes. The layout and buttons resize for touch screens, and everything works with taps exactly as it does with a mouse and keyboard.
What does the % key actually do?
After + or −, it converts the number on screen into that percentage of the value already entered — the exact behaviour a tip or discount needs. Used on its own, it simply divides the number on screen by 100. See the worked tip and discount examples above.
For the Bigger Numbers
This calculator is built for quick, one-off arithmetic. For anything that involves a schedule, interest, or a decision worth getting exactly right, use one of the dedicated calculators below — each one shows the full picture, not just a single total.
Note: This tool performs standard arithmetic for general and everyday use. It is not intended for scientific, engineering or accounting work requiring guaranteed exact decimal precision. All calculations run locally in your browser — nothing you enter is transmitted, logged or stored.