What is a decimal

A decimal is a number that is made up of two parts. The first part is a whole number and the second part represents part of a whole number. These two parts are separated by a dot which is known as a decimal point. Look at the decimal below:

12.4

The 12 is a whole number. The 4 represents part of a whole and is similar to a fraction. The decimal point separates the two parts.  

Understanding decimals

When dealing with whole numbers, we understand that each digit in a whole number has a place value. Look at the number below:

243

This number is two hundred and forth three. In this number, the 2 represents two hundred. The 4 represents four tens or forty. The 3 represents three ones or simply three. With decimals, the numbers after the decimal point have place values as well. Look at the decimal below:

243.7

Read this number as two hundred and forty three point seven. Remember that the digits after the decimal point represent values that are less than one whole. The digit which comes just after the point represents tenths. Therefore the 7 represents seven tenths (7/10). The number above has only one digit after the decimal point. We can say it has one decimal place. Look at the decimal below:

243.75

Read this number as two hundred and forty three point seven five. Notice that this number has two digits after the decimal point. It has two decimal places. As we know, the 7 represents seven tenths (7/10). The digit just after the seven represents hundredths. Therefore the 5 represents five hundredths (5/100).   Decimals can have more than two decimal places. Digits further to the right of the decimal point represent smaller values. For instance, in the decimal 234.758, the 8 represents eight thousandths (8/1000).

Look at the decimals below:

9.5

5.28

21.06

75.83

234.758  

Now study the table below which shows the place value of the digits in each decimal.

Note: There is no limit to the number of decimal places a number can have. However in this course we will focus on adding and subtracting numbers with up to two decimal places.