1. Mathematics
Express as Fractions

2. Lesson Objectives The aim of this powerpoint is to help you…
to express one value as a fraction of another

3. Express as a Fraction
To express one value as a fraction of another you must first ensure that BOTH values have the same type of units.
If they don’t you will have to convert one of them.
Once they both have the same type of units, write the first value over the second value.
Make sure the fraction is valid (i.e. doesn’t contain fractions or decimals within the fraction) by finding an equivalent fraction
If the question asks for the answer in its simplest terms remember to cancel the fraction down if possible.

4. Example 1
Express 50p as a fraction of £2.
First convert 50p into pounds OR convert £2 into pence….. (£2 = 200p)
Now we have express 50p as a fraction of 200p 50
200 ÷ ÷ ≡

5. Example 2
What fraction of 3kg is 1600g?
First convert 1600g into kg OR convert 3kg into grams….. (3kg = 3000g)
Now we need 1600g as a fraction of 3000g
1600
3000 ÷ ÷ ≡

6. Example 3 Note: She got 20 – 13 = 7 wrong
In a test of 20 questions, Cara got 13 questions correct. What fraction of the questions did she get wrong?
Note: She got 20 – 13 = 7 wrong
We have to express 7 as a fraction of 20 7 20

7. Quick Practice For each of the following, express the first value as a
fraction of the second value, giving your answer in its
simplest terms.
A 20p, £5 D 34mm, 5cm
B 15cm, 1m E 30p, £1
C 16g, 80g F 1200m, 4km
Work out your answers before clicking on to the next slide.

8. Answers
A 20p, £5  20p, 500p 20
500
B 15cm, 1m  15cm, 100cm 15
100
C 16g, 80g 16 80 = 1 25 = 1 25
Both numbers end in 0 so divide them BOTH by 10
Now both numbers are even so divide them BOTH by 2 = 3 20
Both numbers end in 5 and 0 so divide them BOTH by 5 = 8 40 = 4 20 = 2 10 = 1 5
You can divide by 2 several times!
Both numbers are even so divide them BOTH by 2

9. Answers (cont’d) 17 3 3 25 10 12 40 10 D 34mm, 5cm  34mm, 50mm 34 50
E 30p, £1  30p, 100p 30
100
F 1200m, 4km  1200m, 4000m
1200
4000 = 17 25
Both numbers are even so divide them BOTH by 2 = 3 10
Both numbers end in 0 so divide them BOTH by 10 = 12 40 = 3 10
Both numbers are in the 4x table so divide them BOTH by 4
Both numbers end in 00 so divide them BOTH by 100

10. What next?
Print out the notes called Frac7. Read them and make sure you answer any questions
If you need more practice, try the worksheet called
ExpFrac-S1.xlsx.
Now move on to the Frac-8 powerpoint