# Decimal numbers

**Decimal numbers** such as 3.14 are used in situations in which we look for more precision than whole numbers provide. As with whole numbers, a digit in a decimal number has a value which depends on the place of the digit.

In the number 3.14, 3 is called the **whole number portion** and 14 is called the **decimal portion**.

There are different types of decimal numbers:

- **Exact decimals or regular numbers**: they are the ones which don’t go on forever, so you can write down all their digits. For example: 0.125

- **Repeating or recurring decimals**: They are decimal numbers which at some point become periodic (repeated over and over). For example: 0.125252525252525... is a recurring decimal, where '25' is repeated forever. The group of repeated decimal digits is called **period**. There are two types:

· **Pure periodic decimals**: 3.1212121212…

· **Eventually periodic decimals**: 4.0312222222…..

- **Irrational numbers**: with no period, as p = 3.14159265…

**Exercise**: classify these numbers:

a) 1,23232323...

b) 1.356565656...

c) 1.234567891011...

d) 3.18

Solutions: a) Pure periodic decimal; b) Eventually periodic decimal; c) Irrational number; d) Exact decimal

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