1. Understanding percentages
Functional Maths
Understanding percentages

2. Let’s talk about percentages
Work in a small group. Talk about what you know about percentages.
When do we see percentages in everyday life?
When do you use percentages at work?
What is a percentage? Why do we use percentages?

3. What is a percentage? 1 100 The word ‘percentage’ comes from the Latin
Per = for, out of (£10 per hour)
Cent = 100 (100 cents in 1$, 100 years in a century) 1
100
Out of

4. can be shown like this… 1 100 Divide the whole into 100 parts
Take 1 part = 1%

5. What does 1% look like?
1% = 1
100

6. What does 10% look like?
10% = =

7. What does 20% look like?
20% = = = 1

8. What does 25% look like?
25% = =

9. What does 50% look like?
50% = =

10. What does 25% look like?
25% = =

11. What does 25% look like?
25% = =

12. What does 25% look like?
25% = =

13. What does 47% look like?
47% = 47
100
Try to visualise trickier percentages
47% = nearly a half

14. Finding a percentage of - a quantity - an amount

15. 1% = 1 = divide by 100 100 Divided by What is 1% of 200?

16. 5% = 5 = divide by 100 then times by 5 100
What is 5% of 200?
What is 5% of 300?
What is 5% of 500?
What is 5% of 4000?
What is 5% of 3476?
What is 5% of 24.50?

17. 5% = 5 = divide by 100 then times by 5 100
What is 5% of 200?
What is 5% of 300?
What is 5% of 500?
What is 5% of 4000?
What is 5% of 3476?
What is 5% of 24.50?
Without a calculator
= 1
100 = 20
So you could divide by 20.
Divide by 10
Take half the answer

18. What is 5% of 450?

19. Three routes, one destination
450 x 5
100
÷ by
5 x 450
100
22.5
÷ by
450 x 5
100
÷ by

20. 450 ÷ 100 x 5
450 divided by 100 (for 1%) . = Multipied by = 22.5
OR You can do 5 ÷ 100 x 450
5 divided by 100 = Multiplied by 450 = 22.5
OR You can do 450 x 5 ÷ 100
450 multiplied by 5 = Divided by 100= 22.5

21. On a calculator you can use the % button.
What is 5% of 450?
450 x 5
100
450 x 5 ÷ 100
On a calculator you can use the % button.
450 x 5%

22. On a calculator you can use the % button.
What is 5% of 450?
450 x 5
100
450 x 5 ÷ 100
On a calculator you can use the % button.
450 x 5%
The % button divides a number by 100

23. Word problems
You pay £550 per month rent.
Your landlord decides to increase your rent by 5%.
How much more rent do you have to pay per month?
A research company asked 12,000 local residents over 65 about their heating bills.
78% of respondents said that they were worried about the cost
of heating.
How many people is that?
Knitwear is on offer in the end of season sale. There is 30% off the ticket price. You buy a jumper with a ticket price of £30.
How much do you pay for the jumper?

24. Questions about percentages
A percentage of an amount
One number as a percentage of another

25. A percentage of an amount
16 out of the 20 students in a maths class are single.
Make the fraction 16 20
Out of

26. 16 out of the 20 students in a maths class are single.
A fraction of an amount
16 out of the 20 students in a maths class are single.
Make the fraction
Divide top by bottom
= 0.8 16 20
Out of

27. A percentage of an amount
16 out of the 20 students in a maths class are single.
Make the fraction
Divide top by bottom
= 0.8
Multiply by
100
= 80% 16 20
Out of

28. A percentage of an amount
16 out of the 20 students in a maths class are single.
What % are married?
80% are single
All students = 100%
100% - 80% are single = 20%

29. A percentage of an amount
478 of the 1400 people interviewed in a survey about healthy eating said they never eat vegetables?
What percentage is that?

30. A percentage of an amount
9 children in a primary school class of 23 children are boys.
What percentage are boys?
What percentage are girls?

31. Word problems
An FE college has been looking at its enrolment figures and found out that 1400 of the 3,500 students are female.
A) What % is female?
B) What % is male?
In a survey of student satisfaction, 1250 if the 1750 people asked said that they were happy with the course.
A) What % is happy?
B) What % is mot happy?

32. What % of income does each represent?

34. 1%
100

35. 25% =
100