The idea, step by step
Equal amounts, different parts
The denominator tells how many equal pieces make one whole. The numerator counts those pieces. If every piece is cut into the same number of smaller pieces, both numbers change but the amount stays the same.
Multiply or divide numerator and denominator by the same non-zero number to make an equivalent fraction. To simplify fully, divide by their greatest common factor. Use equal-sized wholes when comparing pictures.
Counting complete wholes
An improper fraction has a numerator at least as large as its denominator. Divide to find how many complete wholes it contains. The remainder counts the fractional part.
To convert a mixed number, multiply its whole part by the denominator, add the numerator, and keep the denominator. Check by reversing the conversion.
A common trap
Adding the same amount to top and bottom keeps a fraction unchanged.
Instead: Multiply both parts by the same non-zero number instead. For example, .
See the thinking
Simplify a fraction
Simplify .
- 18 and 24 share the greatest common factor 6.
- .
- 3 and 4 share no factor greater than 1.
Find complete wholes
Write as a mixed number.
- 17 divided by 5 is 3 remainder 2.
- Three complete wholes and two fifths give .
- Check: .
Check your understanding
Which equals : or ?
Show answer
Both parts of three fifths have been multiplied by 2.
Your turn
6 questions · 13 marks · Work at your own pace.
Read the questions online
- Simplify .2 marks
- Complete .2 marks
- Write as an improper fraction.2 marks
- Write as a mixed number.2 marks
- Explain why is not in simplest form.2 marks
- One board is m long. Another is m. Are their lengths equal?3 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- Simplify .2 marks
Divide numerator and denominator by 5.
- Complete .2 marks
28 is 7 times 4, so the numerator must also be multiplied by 4.
16 - Write as an improper fraction.2 marks
; keep denominator 5.
- Write as a mixed number.2 marks
23 divided by 6 is 3 remainder 5.
- Explain why is not in simplest form.2 marks
6 and 8 share the factor 2.
- One board is m long. Another is m. Are their lengths equal?3 marks
.
Both amounts use metres.
Yes.
Curriculum reference & lesson scope
Australian Curriculum v9 / SA Curriculum Mathematics
Equivalent fractions and mixed numbers; ordering rational numbers on number lines; adding/subtracting fractions; multiplying/dividing fractions; four operations with decimals; converting between fractions and decimals; multi-step problems and checking estimates.
Official curriculum source ↗