# Understand Metric Units of Length

In this worksheet, students practise converting between metric units of length.

Key stage:  KS 4

GCSE Subjects:   Maths

GCSE Boards:   AQA, Eduqas, Pearson Edexcel, OCR

Curriculum topic:   Ratio, Proportion and Rates of Change, Mensuration

Curriculum subtopic:   Ratio, Proportion and Rates of Change, Units and Measurement

Difficulty level:

### QUESTION 1 of 10

There are a number of units that can be used to describe length, from miles, feet and yards to leagues and metres. We are going to focus on the most common of these which is the metric measurement Metre.

All of the units you will have heard of that have the word metre in them are based around the base unit metre with other words tacked on to describe their relationships.

Kilometre - Kilo means 1000 so 1km = 1000m

Centimetre - Centi means 100 so 1m = 100cm

Millimetre - Milli means 1000 so 1m = 1000mm

Another common conversion that is based on these is that 1cm = 10mm

How to convert.

Step 1: Decide on your conversion factor (i.e. m to km is a conversion of 1000)

Step 2: Either multiply or divide by this number to get your converted numbers,

Example 1: Convert 15cm to metres.

Step 1: Decide on your conversion factor.

100cm = 1m so our conversion factor is 100

Step 2: Multiply or Divide,

You need to think about this a bit. The way I look at this is that a metre is bigger than a cm, so there will be less of them overall.

As there is less of them, we need to divide.

15 ÷ 100 = 0.15 m

Example 2: Convert 1.4km to metres.

Step 1: Decide on your conversion factor.

1000m = 1km so our conversion factor is 1000

Step 2: Multiply or Divide,

You need to think about this a bit. The way I look at this is that a metre is smaller than a km, so there will be more of them overall.

As there is more of them, we need to multiply

1.4 x 1000 = 1400 m

How many cm are in 1 metre?

How many metres are in 1 km?

If I convert 15 cm to mm. Is the answer...

1.5 mm

150 mm

If I convert 4.2 km to m. Is the answer...

4200 m

0.0042 m

Select if the following conversions are correct.

Select if the following conversions are correct.

Match the word with the correct conversion factor

## Column B

Kilo
1000
Centi
100
Milli
10
Milli
1000

Change 210 mm into cm.

Just put the number from you answer, don't worry about the units.

Change 41 m into km.

Just put the number from you answer, don't worry about the units.

Change 370 km into m.

Just put the number from you answer, don't worry about the units.

• Question 1

How many cm are in 1 metre?

100
EDDIE SAYS
The prefix centi- means 100 so there must be 100cm in a metre
• Question 2

How many metres are in 1 km?

1000
EDDIE SAYS
The prefix kilo- means 1000 so there must be 1000m in a kilometre
• Question 3

If I convert 15 cm to mm. Is the answer...

150 mm
EDDIE SAYS
We know that cm - mm is a conversion factor of 10 (there are 10mm in 1 cm). The mistake that people make is to divide here. Try to think that mm are smaller than cm so there will be more of them.
• Question 4

If I convert 4.2 km to m. Is the answer...

4200 m
EDDIE SAYS
We know that km - m is a conversion factor of 1000 (there are 1000m in 1 km). The mistake that people make is to divide here. Try to think that m are smaller than km so there will be more of them.
• Question 5

Select if the following conversions are correct.

EDDIE SAYS
Did you remember to look at the conversions? mm to cm = 10 m to cm = 100 km to m = 1000 Only one of the answers fits the pattern.
• Question 6

Select if the following conversions are correct.

EDDIE SAYS
Did you remember to look at the conversions? mm to cm = 10 m to cm = 100 km to m = 1000 Did you spot the answer that didn't match this pattern?
• Question 7

Match the word with the correct conversion factor

## Column B

Kilo
1000
Centi
100
Milli
1000
Milli
10
EDDIE SAYS
The one that catches people here is that milli can mean two things. 1000 if you are converting to m and 10 if you are converting to cm. You just need to learn this little quirks.
• Question 8

Change 210 mm into cm.

Just put the number from you answer, don't worry about the units.

21
EDDIE SAYS
Did you use the correct conversion factor? 1cm = 10mm. Remember that cm are larger than mm so we need to have more of them. This means we need to multiply.
• Question 9

Change 41 m into km.

Just put the number from you answer, don't worry about the units.

0.041
EDDIE SAYS
Did you use the correct conversion factor? 1km = 1000m. Remember that km are larger than m so we need to have less of them. This means we need to divide.
• Question 10

Change 370 km into m.

Just put the number from you answer, don't worry about the units.

370000
EDDIE SAYS
Did you use the correct conversion factor? 1km = 1000m. Remember that m are smaller than km so we need to have more of them. This means we need to multiply.
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