Also known as the “base-ten” or “denary” system, the decimal system has been used for thousands of years. Like many numeral systems, it is thought that the decimal number system is based on ten and its powers for representing numbers because the concept of counting began with people using their fingers.

Today, it remains the standard system for denoting integer and non-integer numbers. An integer is a whole number, while a non-integer is a portion of a whole number, a negative whole number or zero.

This means that there is a close relationship between decimals and fractions. But while you may be confident about fractions, you may be less familiar with decimals. 

That’s why we’ve written this article. In it, we’ll explain what a decimal number is, what a decimal point is, how decimals relate to fractions and how decimals are taught in school.

A type of non-integer, a decimal number, is a number that’s made up of a whole and part of a whole. Decimal numbers are the numbers in between whole numbers and are expressed in the scale of tens.

Sometimes referred to as a “decimal separator” or a “decimal place”, a decimal point is a dot symbol which is used to indicate that a number is a decimal. It separates the whole number on the left from the digits on the right, which show a value of less than one.

If you want to know more about decimal numbers, keep reading.

Decimal numbers look similar to whole numbers, apart from the fact that they have a decimal point — which looks like a period — in the middle of them. 

The digits on the left of the decimal point will be a whole number, while the digits on the right of the decimal will be less than one whole number but more than zero. 

An example of a decimal number is 14.5, which is in between the whole numbers 14 and 15. 14.5 is more than 14 but less than 15. Because the number 14 is to the left of the decimal point, it tells us that there are 14 whole things. The digit five is to the right of the decimal point, telling us that there are five parts of a whole.

What is a decimal example?

Decimal numbers are often used in everyday life. You may have heard someone referencing the average body temperature as 98.6 degrees, for example, or your favorite radio station might be found on the frequency 98.7.

However, the best example of decimals is money. This is because money is counted in terms of whole dollars. Anything less than a dollar — such as a quarter, a dime or a cent — can be considered a decimal, with the decimal point showing the fraction of the whole dollar. This can also be demonstrated using other currencies, like pounds or euros.

The easiest way to explain decimal numbers is to link them to fractions. This is because both branches of math are about splitting whole numbers into separate parts. 

However, one of the most popular decimal teaching techniques is a one hundred number square or number chart which represents ‘one’ and has squares that are coloured in to represent different parts of the whole or decimals. For example, to demonstrate 0.01, one square is coloured in. Or ten squares are coloured in to demonstrate 0.1. In the case of ‘0.1’, students would need to be taught to knock off the zeros after the decimal points, but to begin with, they may find it easier to understand by writing ‘0.10’. Similarly, they need to know that zeros before the left digit should be disregarded as they won’t change their value. For example, the number 001 is still equal to one.

When studying decimals, you may have come across the term “place value”. Put simply, this is just the value of each digit that appears in a number.

As discussed, when you break a whole number into parts, you get a decimal number. This means a number is then made up of two components: One is a whole number, and the other is a fractional part.

The fractional part of the decimal number is less than one whole number but more than zero. It is positioned to the right of the decimal point — and each place is given a new name the further right you go.

Names of decimal places

  • “Tenths” — The first place after the decimal point
  • “Hundredths” — The second place after the decimal point
  • “Thousandths” — The third place after the decimal point

In the most basic terms, writing out a decimal number is the same as writing the whole number followed by the decimal point and then each digit after the decimal individually. For example, the decimal number for Pi (π) — which is equal to 3.141 — would be written in words as “Three point one four one”.

However, a more formal way to write out decimals would be to write the whole number, use the word “and” to represent the dot and then write the fractional part altogether, using the place value of the last digit. For example, “Three and one hundred forty-one thousandths.

When writing out decimal numbers in this way, note that a decimal number that starts with zero can be expressed in two ways. 0.75, for example, can either be written “Zero point seven five”, or the zero can be dropped, so you would write “Point seven five”.

Another way to write out decimal numbers in words relates to the one-hundred-number square chart. In this instance, you can write “[XX] in a hundred”. So, for the example given earlier, you would write “One in a hundred” to demonstrate one coloured-in square or “ten in a hundred” for ten coloured-in squares.

Alternatively, in fraction form, you would say ‘One-hundredths or ‘Ten-hundredths (which would be simplified to ‘one tenth’). Continuing in this vein, 0.75 could be written as “Three-quarters”.

Or you could take it a step further and write 0.75 as “Seventy-five percent” (or “75 percent”).

When it comes to writing out decimals in monetary terms, there are different rules. For example, instead of writing $3.14 as “Three point one four” or “Three and fourteen hundredths”, you would write “Three dollars and fourteen cents” or “Three fourteen”.

Decimal numbers can be divided into two categories:

  1. Like decimals — These are decimal numbers with the same number of digits after the decimal point. For example, 0.75 and 3.14 both have two digits after the decimal point.
  2. Unlike decimals — These are decimal numbers with a different number of digits after the decimal point. For example, 0.7 and 3.141 have one and three digits after the decimal point.

Both decimals and fractions are about splitting whole numbers into separate parts.

A decimal number is a number that’s made up of a whole and part of a whole. Decimal numbers are the numbers in between whole numbers and are expressed in the scale of tens.

Sometimes referred to as a “decimal separator” or “decimal place”, a decimal point is a period symbol which is used to indicate that a number is a decimal. The digits on the left of the decimal point will be a whole number, while the digits on the right of the decimal will be less than one whole number but more than zero. 

Decimal numbers can be divided into two categories: Like decimals, which have the same number of digits after the decimal point and unlike decimals, which have a different number of digits after the decimal point.