He **adjective** **decimal** It can be applied with reference to that which is one of the ten identical parts into which something is divided. The term is often used in the field of **mathematics** .

It is called **decimal system** to one that is formed by units that are divisors or multiples of ten with respect to the main unit of the class. He **decimal numbering system** , in this framework, is based on the use of quantities represented by the **powers** of number ten as a base.

The **symbols** which employs the decimal numbering system are **0** , **1** , **2** , **3** , **4** , **5** , **6** , **7** , **8** ** and 9** . This system is

**positional**: The value of the digit is linked to the position it occupies in the figure.

Let's see below how we should interpret in a number belonging to the decimal system the **position** of each of its figures. First, we must remember that we learn to name the numbers mentioned in the previous paragraph as independent elements of a number, and from our basic education we are focused on the decimal system; we call the symbol "four" *4*, for example, without thinking that in the number *421* it is no longer read in this way, but "four hundred".

Continuing in the decimal system, if we begin to analyze a **integer numbers** from its right end, we will find the following positions or columns: units, tens, hundreds, units of thousands, tens of thousands, hundreds of thousands, units of millions and so on.

As explained in a previous paragraph, to find each of these values it is necessary to multiply a number by *ten* raised to a different power; in the **column** of the units, said power is *zero*, and it increases by one unit as we move to the left (thousand units, for example, are obtained by multiplying the corresponding number by *ten* raised to the *three*).

The need to classify the numbers of numbers greater than or equal to *ten* in different categories, so to speak, it is far from being an arbitrary or merely aesthetic issue: thanks to this division into groups it becomes much easier to resolve **operations** arithmetic, both the simplest and the most complex.

Only by observing the steps we take to solve a simple sum can we appreciate the comfort offered by the recognition of different positions or columns within the decimal system. If we add *4* plus *7*, for example, as the **result** is greater than *9* we must break it down in the column of the units (where we will place a *1*) and in the tens (where another will go *1*).

A **decimal number** it is one that has an entire part and a fractional part, separated from each other by a **coma** (**,** ) or for a **point** (**.** ). The number **5,8** , for example, has a whole part (**5** ) and a fractional or decimal part (**0,8** ).

It should be noted that the symbol used to mark the separation between the fractional part and the entire part is known as **decimal separator** . In some countries, the decimal symbol is the comma, while in others the **point** . In this way, the number **5,8** can be written **5.8** In some regions.

Decimal numbers also have their own system of **nomenclature** , which gives each position a different name. With respect to the figures to the left of the comma (or the corresponding decimal separator, depending on the region), the same labels mentioned above are used; the positions that are located to the right, however, are called tenths, hundredths, thousandths, and so on.

He **metric system** , on the other hand, is a **system** of measures and weights, with the kilogram and the meter as base units, whose units are divisors or multiples of ten.