Curta Calculator Simulator & Tutorial

WELCOME TO THE CURTA

The Curta is a mechanical calculator that performs addition, subtraction, multiplication and division with amazing speed and accuracy.

Use the tutorial sections to learn how to operate it.

QUICK OVERVIEW

Sliders (1–8): Set the value of each column.
Crank (top): Turn clockwise.
- Add mode (+): adds the number.
- Subtract mode (−): subtracts the number.
Result Dial: Shows the 11-digit result.
Revolution Counter: Counts crank turns.
Carriage Select: Chooses which decimal position the crank affects.
Counter Reverse: Changes direction of the revolution counter.

WHAT EACH PART DOES

12 34 67 8

1Crank Handle 2Result Dial (11 digits) 3Revolution Counter (6 digits) 4Carriage Position Indicator 5Sliders (Carriages 1–8) 6Carriage Select 7Add / Subtract Mode 8Counter Reverse Lever

ADDITION

Press RESET ALL.
Set the first number using the eight sliders.
Leave the carriage at position 1.
Select ADD and turn the crank once.
Set the next number and turn once again.

SUBTRACTION

Enter the starting number and crank once in ADD mode.
Set the number to subtract.
Select SUBTRACT.
Turn the crank once.

MULTIPLICATION

Multiplication is repeated addition. Each carriage position represents a power of ten.

Example: 123 × 24

Set 123.
Crank 4 times at carriage 1.
Move to carriage 2.
Crank 2 times.

DIVISION

Division uses repeated subtraction. The result dial holds the remainder and the counter records quotient digits.

SHORTCUTS

Multiply by 9: add once one carriage to the left, then subtract once in the original position.
Multiply by 99: add at carriage 3 and subtract at carriage 1.
Trailing zeros: shift the carriage instead of entering zeros.
Choose the smaller factor as multiplier: this reduces crank turns.

ABOUT THIS SIMULATOR

This webpage models the arithmetic behavior and visual layout of a Curta Type I calculator for educational use.

A real Curta is a precision mechanical instrument. Never force its crank, carriage, clearing rings or mode controls.