Unit Conversion
Multiply by conversion factors equal to 1 to change units.
Key idea
Multiply by conversion factors equal to 1 to change units.
In depth
Multiply by a conversion factor equal to 1 (like 100 cm / 1 m) so the units cancel and the quantity stays the same. Writing the units makes mistakes visible.
Worked example
3.5 km to m: 3.5 km × 1000 m/1 km = 3500 m.
Formula
Real-world uses
- Converting kilometres to miles for travel
- Changing litres to millilitres in medicine
- Cooking measurements
Common mistake
Multiplying when you should divide. Check that the units you want remain.
How to learn this
- Read the key idea and say it in your own words.
- Work through the worked example, then try a similar problem.
- Use the interactive lesson’s visual and mini-quiz to check the pattern.
Frequently asked questions
What is Unit Conversion?
Multiply by conversion factors equal to 1 to change units. It is a topic at the intermediate level in Arithmetic & Number Sense.
What is the formula for Unit Conversion?
The key formula is 1 km = 1000 m.
Where is Unit Conversion used in real life?
Real-world examples: Converting kilometres to miles for travel; Changing litres to millilitres in medicine; Cooking measurements.
What should I learn before Unit Conversion?
Make sure you are comfortable with Scale Factor and Maps, the previous topic in Arithmetic & Number Sense.
What is a common mistake with Unit Conversion?
Multiplying when you should divide. Check that the units you want remain.
How can I practise Unit Conversion?
Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.
What comes after Unit Conversion?
Move on to Length, Mass and Capacity next.
Related intermediate topics in Arithmetic & Number Sense
- Long Multiplication – Multiply by each digit of the multiplier, shift by place value, then add partial products.
- Long Division – Divide, multiply, subtract and bring down repeatedly to get the quotient.
- Factors and Multiples – Factors divide a number exactly; multiples are its products with whole numbers.
- Divisibility Rules – Quick tests: by 2 last digit even, by 3 digit-sum divisible by 3, by 5 ends 0/5, by 9 digit-sum divisible by 9.
- Prime Numbers – A prime has exactly two positive divisors: 1 and itself.
- Composite Numbers – Numbers greater than 1 with more than two factors.