Linlithgow Academy · Mathematics · S2 Revision

Fractions

Proper and improper fractions, mixed numbers, and adding to or subtracting from one.

Key ideas

1 = 5/5+ 3/5

a whole one   the fraction added   the fraction taken away

Proper and improper fractions

Fractions

Proper or improper?

Is 94 a proper or an improper fraction?(1 mark)
4/44/41/4
Compare the top and bottom.Top = 9, bottom = 49 > 4, so 94 is improper✓1
In plain EnglishThe top is bigger than the bottom, so it is top-heavy. It is more than one whole.
Marking points
M1 Improper, since 9 > 4

Mixed numbers

Fractions

Mixed number to improper fraction

Write 234 as an improper fraction.(2 marks)
4/44/43/4
Change the wholes into quarters.2 = 84✓1
In plain EnglishEach whole one is 4 quarters, so 2 wholes are 2 × 4 = 8 quarters.
Add the fraction part.84 + 34 = 114✓2
In plain EnglishAdd the tops: 8 + 3 = 11. The bottom stays as 4.
Shortcut: whole number × bottom, then add the top. 2 × 4 + 3 = 11, so 2¾ = 11/4.
Marking points
M1 2 = 8/4
M2 11/4
Fractions

Improper fraction to mixed number

Write 135 as a mixed number.(2 marks)
How many whole ones?13 ÷ 5 = 2 remainder 3✓1
In plain EnglishEach whole one is 5 fifths. 13 fifths makes 2 wholes (10 fifths) with 3 fifths left over.
Write the mixed number.135 = 235✓2
In plain EnglishThe 2 whole ones, and the 3 fifths left over.
Marking points
M1 2 remainder 3
M2 2 3/5

Adding to one

Fractions

Adding a fraction to one

Calculate 1 + 35. Give your answer as an improper fraction.(2 marks)
1 = 5/5+ 3/5

a whole one   the fraction added   the fraction taken away

Write 1 as fifths.1 = 55✓1
In plain EnglishThe fraction is in fifths, so write one whole as 5 fifths.
Add the tops.55 + 35 = 85✓2
In plain English5 fifths and 3 more fifths make 8 fifths. The bottom stays as 5.
Marking points
M1 1 = 5/5
M2 8/5
Fractions

Adding a fraction to a whole number

Calculate 2 + 34. Give your answer as an improper fraction.(2 marks)
1 = 4/41 = 4/4+ 3/4

a whole one   the fraction added   the fraction taken away

Write 2 as quarters.2 = 84✓1
In plain EnglishEach whole is 4 quarters, so 2 wholes are 8 quarters.
Add the tops.84 + 34 = 114✓2
In plain English8 quarters and 3 more quarters make 11 quarters.
Marking points
M1 2 = 8/4
M2 11/4

Subtracting from one

Fractions

Subtracting a fraction from one

Calculate 1 − 38.(2 marks)
1 = 8/8 take away 3/8

a whole one   the fraction added   the fraction taken away

Write 1 as eighths.1 = 88✓1
In plain EnglishThe fraction is in eighths, so write one whole as 8 eighths.
Take away the tops.88 − 38 = 58✓2
In plain EnglishStart with 8 eighths and take 3 away. 5 eighths are left.
Marking points
M1 1 = 8/8
M2 5/8
Fractions

Subtracting from a whole number

Calculate 3 − 25. Give your answer as an improper fraction.(2 marks)
1 = 5/51 = 5/51 = 5/5 take away 2/5

a whole one   the fraction added   the fraction taken away

Write 3 as fifths.3 = 155✓1
In plain EnglishEach whole is 5 fifths, so 3 wholes are 3 × 5 = 15 fifths.
Take away the tops.155 − 25 = 135✓2
In plain English15 fifths take away 2 fifths leaves 13 fifths.
Marking points
M1 3 = 15/5
M2 13/5

Problems in context

Fractions

A problem in context

Amy has 1 bar of chocolate. She eats 26 of it. What fraction of the bar is left?(2 marks)
1 = 6/6 take away 2/6
Start with one whole bar.1 = 66✓1
In plain EnglishThe bar is split into sixths, so the whole bar is 6 sixths.
Take away what she ate.66 − 26 = 46✓2
In plain English6 sixths take away 2 sixths leaves 4 sixths.
You may also see this written as 2/3, which is the same amount simplified.
Marking points
M1 1 = 6/6
M2 4/6

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Your turn

Type fractions with a slash, like 8/5. Type mixed numbers with a space, like 2 3/4. Give answers as improper (top-heavy) fractions unless the question says otherwise. Stuck? Tap Need a hint?