What Leonardo da Vinci invention used a rotating cylinder to add numbers mechanically?

Leonardo da Vinci’s invention using rotating cylinders to add numbers mechanically was a mechanical calculator.

A drawing in the Codex Madrid I, rediscovered in the 1960s, shows a calculating device made from a series of geared wheels and cylinders. The arrangement appears capable of carrying values from one digit position to the next, which is the essential difficulty in mechanical addition. Leonardo’s design is usually presented as an early calculating-machine concept rather than as a proven completed calculator.

The machine is sometimes called Leonardo’s calculator or Leonardo’s adding machine. It should not be confused with the later Pascaline, built by Blaise Pascal in the 17th century and associated with practical mechanical calculation. Because the surviving drawing does not provide every construction detail, historians and engineers have debated how fully the mechanism would have worked.