What Leonardo da Vinci invention concept used gears to perform calculations?

Leonardo da Vinci’s mechanical calculator concept used geared wheels to perform calculations.

Leonardo drew a calculating machine in the Codex Madrid I, a manuscript dated to 1490–1500. The design includes a series of interlocking gears arranged so that turning one wheel would drive others in controlled numerical steps. It is commonly identified as an early mechanical calculator concept.

The drawing was not a complete operating calculator with surviving instructions, and no original machine is known to have been built by Leonardo. Its importance lies in showing how numerical operations could be represented mechanically through gear ratios and place-value movement.

Leonardo’s concept predates the well-documented calculating machines of Blaise Pascal by more than a century. It should not be confused with a slide rule, which uses logarithmic scales, or with a clock, whose gears primarily measure time rather than carry numerical operations.