In the previous post about Hundreds, Tens and Units we started to look at place value and that the order of digits within a numbers makes a difference to the value of the number. In this post, we’ll learn about decimals and place value too.
Any number that has a decimal point in it, is usually referred to as a ‘decimal’.(1) It just means that have a number which isn’t a whole number. It has a fraction or ‘part’ of 1 in it. The one in the picture at the top of this page is one of the most famous decimal numbers: Pi. Here are some examples of decimals you might seen in every day life:
The most common examples of these is probably money: pounds and pence. There are 100 pence in £1 so you’ll see tenths and hundredths. (0.1 and 0.01) as well as the usual hundreds, tens and units.
We can represent these as:
Tenths = t
Hundredths = h
Here’s a summary of place values and abbreviations.
But there are decimals everywhere, and usually we can say them or write them down in more than one way.
|0.3||Zero units and three tenths||3/10||3 x 0.1|
|0.75||Zero units and 75 hundredths||75/100||75 x 0.01|
|1.04||1 unit, zero tenths and and four hundredths||4/100 plus 1||4 x 0.01 plus 1|
Right, let’s put this into practise:
Q1 – How many hundreths are there in 0.19?
Q2 – How many thousandths are there in 1.05898
Q3 – How many tenths are there in 12.49? (Hint: think how many 10 pences you’d have if it were in money?)
I hope you enjoyed this post. If you have any questions or have suggestions for future topics contact me.
(1) The word ‘decimal’ actually refers to the fact that our number system is based on the number 10. Each place value holds a number from 0 to 9 (ten numbers) and then once we reach 9 we go to the next place or column. Other examples of number systems based on different numbers are binary (based on 2) and hexadecimal (based on 16).