A free and simple Reverse Polish Notation calculator.
In Reverse Polish Notation you enter the operands
first and the operator last. Instead of writing 3 + 4 =,
you type 3, push it with ENTER, type
4, then press +. The result appears
immediately.
Numbers live on a stack. Pressing ENTER pushes the number you just typed onto the stack. An operator such as + takes the top two numbers, combines them, and puts the single result back. This is why no parentheses are ever needed: you control the order yourself.
The lowest line of the display is the working register, called
X. It always shows a value — 0 when
nothing has been typed yet.
The screen shows several stack lines at once, oldest at the top and the working value (X) at the bottom, drawn larger. The line above X is Y, then Z, and so on.
While you are typing a number it appears on the bottom line. As soon as you press ENTER or an operator, the value is committed to the stack and the lines shift up.
| Key | What it does |
|---|---|
0 – 9 | Type the digits of a number. |
· | Decimal point. |
± | Flip the sign of the value on the X line. |
+ − × ÷ |
Combine Y and X (Y is the first operand) and leave the result in X. |
ENTER | Push the typed value onto the stack; the input line resets to 0. |
SWAP | Exchange the X and Y values. |
DROP | Remove the X value from the stack (the lines shift down). |
C | Clear only the current (X) line, setting it back to 0. |
CLEAR | Clear the entire stack. |
◄ | Backspace: erase the last digit. When nothing is left it shows 0 rather than dropping a stack value. |
Subtraction and division use Y first: 10 ENTER 3 − gives
7 (Y − X), and 8 ENTER 2 ÷ gives
4 (Y ÷ X).
| Goal | Keys | Result |
|---|---|---|
| Add 3 and 4 | 3 ENTER 4 + | 7 |
| 10 minus 3 | 1 0 ENTER 3 − | 7 |
| 8 divided by 2 | 8 ENTER 2 ÷ | 4 |
| Make 5 negative | 5 ± | -5 |
| (2 + 3) × 4 | 2 ENTER 3 + 4 × | 20 |
Notice how (2 + 3) × 4 needs no
parentheses: you compute the sum first, then multiply — exactly the
order you press the keys.
On Windows the calculator runs as a frameless, transparent window shaped to the rounded body — there is no title bar.
– and ✕ buttons at the right of the branding
strip.