The abacus emerged as the first known calculator. Some abacus models appeared in China, Rome and other regions, but all with similar functioning. There are still several abacus models today, the most common being the horizontal or vertical rod abacus.
With the abacus, we can do calculations and represent numbers in the decimal numbering system. Remembering that the decimal numbering system is one in which all numbers that exist are formed by combinations of digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. In this system, numbers are classified according to their classes and orders:
Note the ranking of number 16,224: A ten thousand, 6 thousand units, 2 hundreds, 2 tens and 4 units.
We have in the table the number 16,224, which is read as follows: sixteen thousand, two hundred and twenty-four. We can represent this number on the abacus, as shown in the figure below.
Representation of the number 16,224.
When working with the abacus, it is important to remember that each rod can only hold a maximum of 9 pebbles, as in the decimal numbering system each order only admits from 0 to 9 units. Both in the table we saw and in the abacus, if we need to represent the number 10, for example, we should use a ten, placing the 1 in the second order. We can represent any number using the abacus, just increase the number of rods as needed, thus increasing the number of orders.
