Applet: Genaille-Lucas Rulers

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Genaille-Lucas Multiplication Applet

Division Applet

Genaille–Lucas rulers (also known as Genaille's rods) is an arithmetic tool invented by Henri Genaille, a French railway engineer, in 1891. The device is a variant of Napier's bones.

By representing the carry graphically, the user can read off the results of simple multiplication problems directly, with no intermediate mental calculations.

Example: 874 x 7

Start reading the result by the
first number in the right hand column (8),
and follow the triangles:

To multiply a multi-digit number by a multi-digit number, calculate partial products and add:

Example: 874 x 73 = 874 x 70 + 874 x 3

874 x 7 = 6118
874 x 3 = 2622

add    :             61180

                       +2622
                     _________

result:             63802

Genaille-Lucas Division Applet

Neper Applet

Links

Genaille–Lucas rulers (Wikipedia)

Early Calculation (Ed Thelen)

Napier's Bones, Genaille-Lucas Rulers (Georgi Dalakov)

Napier's Bones and the Genaille-Lucas Rulers (Brian Borchers)

Qui est Henri Genaille?

Digitale Rechengeräte

Rods for Multiplication and Division

Updated: 2023, Oct 12