In today’s post, we are going to learn a little more about rational numbers.

In an earlier post, we saw how to represent numbers on a number line and in another, what types of rational numbers exist.

Now we are going to get to know them in a bit more detail.

##### Properties of Rational Numbers

**Rational numbers** are those that can be represented as a ratio of two whole numbers. It is to say, that we can represent them as a fraction *a/b*, where *a* and* b* are whole numbers and *b* is a number other than zero.

The term ”rational” comes from the word ratio, meaning part of a whole. (for example: *”We had a ratio of three per person.”*)

**Each rational number can be represented by infinite equivalent fractions. **For example, the rational number 2.5 can be represented by the following fractions:

And by all the fractions equivalent to these.

The **set** of all **rational numbers** is represented by the following symbol:

Remember that any whole number is also a rational number and can be represented as a ratio of two whole numbers.

For example, the number 5 can be represented by the following fractions:

This means that the set of **whole numbers** is **contained** within the set of **rational numbers**. Mathematically we write it as:

To place the numbers on a number line, or real numbers, there are numbers that cannot be represented as a ratio of two whole numbers.

These numbers are called** irrational numbers**, and the most well known are these:

##### The Rational Numbers of Ancient Egypt

Rational numbers emerge with the need to **distribute** a quantity * D* in

*parts, where*

**d***is not a multiple of*

**D***.*

**d**To calculate the amount that will be distributed to each part, you need to perform the operation * D:d*, which does not result in a whole number because

*is not a multiple of*

**D****.**

*d*To find the result of this operation, there are numbers that appear and are able to represent the form * D/d*, but they are different from whole numbers.

In** Ancient Egypt**, they already had made these types of ”parts of an integer” deals using almost exclusively unit fractions, that had 1 as the numerator. It is to say that we can represent 1/b as a fraction, where b is a positive whole number.

These unit fractions were represented by hieroglyphics in the shape of an ”open mouth” that represented the vinculum (line in a fraction), and a numerical hieroglyphic written below, which represented the denominator of the fraction.

For example, to represent 1/4 they wrote it in the following way:

Any non-unit fraction was represented as the sum of different unit fractions. Therefore, the sums of unit fractions are known as Egyptian fractions.

What did you think of this post? Would you like to get to know rational numbers better? If this is the case, share the post so that others can learn as well.

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### Learn More:

- Fractions and Rational Numbers
- Understand What a Fraction Is and When It Is Used
- Using Lego Blocks to Help with Addition of Fractions
- Understanding Fractions: “If the Whole Is Made of 8 Parts, How Can I Have 11?”
- Equivalent Fraction and Simplified Fraction

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