What type of machine did Leonardo da Vinci sketch for automatically producing arithmetic calculations?

Leonardo da Vinci sketched a mechanical calculator for automatically producing arithmetic calculations.

The concept is associated with a drawing in the Codex Madrid I, dated to 1493. It used a series of geared wheels arranged so that turning one wheel could carry a value to the next place, a principle needed for multi-digit calculation. The machine is often described as an early odometer-like calculating device.

Leonardo's drawing does not provide a complete operating manual, and no original calculator by him is known to survive. Modern reconstructions therefore rely on interpretation of the gears and their intended relationships.

The device should not be confused with a modern electronic calculator or with an abacus. It was a proposed mechanical system using visible rotating parts. Its significance is that it demonstrates Leonardo's understanding of numerical carry mechanisms centuries before electronic computing.