Types Abacus: Abacus Napier - Abacus Card
Types Abaci Abacus Napier, Abacus Card Image Source Wikimedia Commons License: CC 3.0, 2.5. ... Attribution: Luis Garcia Napier or Card Abacus Inventor John Napier, built several types of abacus, including one of the most important is: the Abacus card. Napier or Card Abacus Structure The apparatus consists of a wooden box inlaid with bone. The top section contains "bones" and at the bottom the card abacus. This card abacus consists of 300 cards stored in 30 boxes. One hundred of these cards are covered with numbers (known as the "number cards"). The remaining two hundred cards contain small triangular holes, which, when placed on top of the number cards allow the user to view only certain numbers. By positioning these card's Abacus can, multiplication can be done to limit number of 100 digits in length, on the other number 200 digits long. Also, the doors of the box containing the first powers of numbers, the coefficie...