Home learning focus
Learn how to write decimals using place value columns.
This lesson includes:
- one learning summary
- four interactive activities
Decimals in daily life
Decimals are all around you:
- They are used to write amounts of money (£1.99).
- You see them when baking or on packets of food to show weight (1.5 kg of flour).
- They’re used in length (1.45 km).
- Even time uses decimals (10.15 seconds).
That is why it is important to understand how to write decimals and understand their place value.
Tenths and hundredths
We use a decimal point to separate the whole from the parts of a whole.
When one whole is divided into 10 parts, you call it a tenth.
When one whole is divided into 100 parts, you call it a hundredth.
You often see tenths and hundredths written as fractions, for example ⁹¹/₁₀₀.
Have a look at last week's lessons on tenths and hundredths for a reminder.
The place value columns for tenths and hundredths look like this:
Let's look at how you write decimals.
How would you write thirteen and fifty-two hundredths as a decimal?
Use your knowledge of place value and partitioning. Thirteen is made up of one ten and three ones.
There are fifty-two hundredths. This is made up of 5 tenths and 2 hundredths. These numbers go after the decimal point.
So thirteen and fifty-two hundredths is written 13.52
Write ²¹/₁₀₀ as a decimal.
Use your knowledge of place value: ²¹/₁₀₀ (21 hundredths) is made up of 2 tenths and 1 hundredth.
In a place value chart that would look like this:
There are no ones, so you write zero in the ones column to show this!
If you have no ones at all, you must write a zero before the decimal point. This is to show that it is a number smaller than one.
Rearrange the numbers into the correct place value columns.
Guardians: Defenders of Mathematicia
Play the Palace of Place Value level in Guardians: Defenders of Mathematicia to test your knowlege of decimals and place value.
There's more to learn
Have a look at these other resources around the BBC and the web.