He **symbol** that appears in propositions, algorithms, formulas and functions and that adopts different values is called **variable** . According to their characteristics, one can distinguish between different kinds of variables.

The **quantitative variables** are those who adopt **numerical values** (i.e. figures). In this way they differ from **qualitative variables** , which express qualities, attributes, categories or characteristics.

It is important at this point that we proceed to know the etymological origin of the two words that shape the term at hand:

-Variable comes from Latin, specifically derived from "variabilis", which can be translated as "which can change its appearance". It is the result of the sum of two components: the verb "variare", which is synonymous with "change of aspect", and the suffix "-able", which is used to indicate possibility.

-Quantitative, on the other hand, comes from Latin as well and is made up of the union of several elements of this language: "quantum", which is equivalent to "quantum", and the suffix "-tive". This is used to record a passive or active relationship.

At **set** of the quantitative variables, we can also recognize several types of variables. The **continuous quantitative variables** they can adopt any value within the framework of a certain interval. According to **precision** of the instrument that performs the measurement, there may be other values in the middle of two values. The **height** of a person, for example, is a continuous quantitative variable (they can be values such as *1.70 meters*; *1.71 meters*; *1.72 meters*, etc.).

With regard to continuous quantitative variables, we can establish that other simple examples would be the mass of any object or the height of a building.

The **discrete quantitative variables** instead acquire **values** that are **separated from each other** on the scale In other words: there are no other values among the specific values that the variable acquires. The number of pets a person has is a discrete quantitative variable: a woman can have *2*, *3* or *4 dogs*, but never *2,5* or *3.25 dogs*. In this case, *2* and *3* they are values that the variable is in a position to adopt, without any other possible value in the middle of both.

Other examples of discrete quantitative variables can be these:

-The number of children a person has.

-The number of animals that a farmer owns.

-The set of vehicles that exist in a dealership.

Both types of quantitative variables can be combined into one **poll** or in one **interview** . The applicant for a job can be asked how much he weighs (continuous quantitative variable) and how many children he has (discrete quantitative variable).

In addition to all of the above it is important to know another series of interesting facts about quantitative variables, such as the following:

-As a general rule, when it comes to graphing them, it is decided to make use of integral diagrams and differential diagrams, which are what they use to show the so-called relative frequencies.

-In the same way, you can also use what are the bar charts.