Instrument designed in 1916 to help children learn multiplication tables. Simply position the monkey’s feet on the numbers to multiply and read the result in his hands.

The exhibited model was built in 1916 and was manufactured by The Educational Toy MFG in the United States.

We can prove geometrically that when the foot is stationary and the other foot moves on a fixed line going through the first foot, the trajectory of the point designated by the hands of the monkey is a straight line. So the numbers giving the results are all on parallel lines.