rpn

A little room to think.

FOUR-LEVEL STACKREADY

T0

Z0

Y0

X0

REVERSE POLISH. SIMPLY.NO EQUALS NEEDED.

A DIFFERENT ORDER

Numbers first.
Then the operation.

To add 12 and 8, press:

12enter8+→ 20

Enter copies X into Y. Typing the next number replaces X. An operation uses Y and X, leaving its result in X.

x↔y S: Swap X and Y
R↓ R: Roll all four levels down
√x Q: Square root of X
1/x I: Reciprocal of X
± N: Change the sign of X
← ⌫: Delete a digit, or clear X
AC Esc: Clear the whole stack

Inspired by the HP 35s: four stack levels, automatic stack lift, and a repeating T register. Uses standard JavaScript number precision, with up to 15 significant digits displayed.

Follows your device’s light or dark theme. Add to your home screen from your browser’s menu. This first version needs a connection to load; reloading clears the stack.