Each set of Napier's bonus consisted of ____ rods.
Each set of Napier's bonus consisted of 11 rods.
Napier's bones are three-dimensional, square in cross section, with four different rods engraved on each one. A set of such bones might be enclosed in a convenient carrying case. A rod's surface comprises 9 squares, and each square, except for the top one, comprises two halves divided by a diagonal line.
In 1617, shortly before his death, Napier developed a mechanical method for performing multiplication and division. This method, known as "Napier's bones," was based upon manipulation of rods with printed digits. The rods were made of bone, ivory, wood, or metal.
To calculate 83 × 24, place the multiplier and the bones for the number being multiplied (i.e. the '8' and '3' bones for 83) side by side as shown below. To find the product first multiply by 4 and then multiply by 20, and add just as you would for long multiplication to find the answer.