This is the calculator you would keep on your desk: digits, the four operations, a percent key, a square root, memory and a change-sign key. What it adds is a paper tape. Every time you press equals, the full calculation and its result are printed on the tape beside the keypad, so you can check your work, copy it, or click a line to reuse the result.
How to use the basic calculator
- Type a number with the on-screen keys or your keyboard. Use ⌫ to fix a mistyped digit and CE to clear just the current entry.
- Press an operation key (+, −, ×, ÷). The key stays highlighted so you can see which operation is waiting; pressing a different operation replaces it.
- Type the next number and press =. The answer appears in the display and a new line is printed on the tape.
- To keep going from the answer, press another operation. To start fresh, simply type a new number.
- Click any line on the tape to load that result back into the display.
What each key does
| Key | What it does |
|---|---|
| AC | Clears the display and the pending calculation (memory and tape are kept) |
| CE | Clears only the number you are typing |
| ± | Changes the sign of the current number |
| % | Turns the current number into a percentage (see below) |
| √ | Square root of the number on the display |
| MC / MR | Clear memory / recall the stored number |
| M+ / M− | Add the display to memory / subtract it from memory |
Order of operations
Many pocket calculators work strictly left to right, so 12 + 3 × 4 gives 60. This calculator follows the standard order of operations instead: it multiplies 3 × 4 = 12 first and then adds, giving 24. That matches what a scientific calculator, a spreadsheet and a math teacher would expect. If you want each step applied as you go, press = after each operation. For a step-by-step breakdown of longer expressions, use the order of operations calculator; for long columns of figures, the adding machine keeps a subtotal for you.
How the percent key works
The percent key is designed for everyday price math:
Discount: a $80 jacket is 25% off. Type 80 − 25 % = and the display shows 60.
Sales tax: $200 plus 7.5% tax. Type 200 + 7.5 % = to get 215.
Percentage of a number: 18% of 64.8. Type 64.8 × 18 % = to get 11.664.
After + or −, the percentage is taken of the number before it. After × or ÷, the key just divides by 100. For other percentage questions — what percent one number is of another, or a percent change — the percentage calculator shows each step.
Using memory for a running total
Memory is handy when you need to add up several products. To total 3 items at $4.25 and 2 items at $6.50:
- Type 3 × 4.25 = (12.75), then press M+.
- Type 2 × 6.5 = (13), then press M+ again.
- Press MR: the display shows 25.75, the total of both lines.
Precision and very large numbers
Results are rounded to 12 significant digits to hide the tiny binary rounding errors all computers make, so 0.1 + 0.2 shows 0.3 and 1 ÷ 3 shows 0.333333333333. Answers of a quadrillion or more switch to scientific notation; for example 99,999,999 × 99,999,999 displays as 9.9999998 × 10¹⁵. When you need every digit of a huge product, the long multiplication calculator works with exact digits.
Dividing by zero shows “Cannot divide by zero.” Press AC or CE to continue.
Frequently asked questions
Does this calculator follow the order of operations?
Yes. If you type a chain such as 12 + 3 × 4, multiplication and division are done before addition and subtraction, so the answer is 24, not 60. Press = after each step if you want a running total instead.
How does the percent key work?
After + or −, the percent key takes a percentage of the first number: 200 + 7.5% = 215 and 80 − 25% = 60. After × or ÷ it simply divides by 100, so 64.8 × 18% = 11.664.
What do MC, MR, M+ and M− do?
They manage one stored number. M+ adds the number on the display to memory, M− subtracts it, MR recalls the stored number and MC clears it. The small M above the display shows what is stored.
Is my calculation history saved?
The paper tape and the memory value are kept in your browser's local storage on this device only. Nothing is sent to a server. Use Clear tape to erase the history or Copy tape to paste it into a document.
Can I type with my keyboard?
Yes. Type digits and the decimal point, use + − * / for the operations, Enter or = to calculate, Backspace to delete a digit, Delete to clear the entry and Esc to clear everything. R takes a square root and N changes the sign.