Where do I start?
If you are comparing the length of things, and they are using the same unit of measurement, you can compare their numbers. If you want the longest, you choose the biggest number. Shortest? Smallest number.
What if they aren't the same?
Check out which units you're using - millimetres (mm), centimetres (cm), metres (m) or kilometres (km). Decide which one you'll convert, and convert to the unit you want to work with.
You may want to use this conversion chart to help you.
Conversion chart
To convert to the next unit, such as km to m, or mm to cm, have a look at this video that sets out the steps you need to take.
Worked Example
Question 1
Convert $25.97$25.97 millimetres to centimetres. Write your answer as a decimal.
$25.97$25.97 mm = $\editable{}$ cm
Bigger jumps
If we need to convert from mm to m, or even mm to km, this might seem like a huge step. We can do one step at a time though, and complete our conversion in smaller chunks.
In this video, we work out whether to multiply or divide, based on the direction we need to convert to and from.
Worked Example
Question 2
Convert $6.22$6.22 km to cm.
$6.22$6.22 km = $\editable{}$ cm
Using what we've learnt
Now it's time to solve some problems that use length. This is where we can see why we'd want to convert units of measurement, and how to use this to solve our problem.
Worked Example
Question 3
Joanne is $156$156 cm tall. Victoria is $1.14$1.14 m tall.
Work out the height of Victoria in centimetres.
Who is taller?
Joanne
AVictoria
B
Always check first to see if you have the same unit of measurement. If not, you'll need to convert one (or more) of your units. Then you need to multiply of you are converting to smaller units, because there will be more of them, or divide if you are converting to bigger units.