High Interest

Starter of The Day Transum Mathematics Topics

Fiona Ryan, Moonta Area School
I used this activity as a calculator skills activity for my Special Education class.
Transum,
This is your chance to get your students to practise the techniques they have learned. This really is a 'skill for life' activity and falls in the financial maths camp too. The ability to mentally calculate simple percentages is so useful but many students find their way through school without learning the tricks and tips. This starter needs discussing with the class when everyone has had a chance to do it. Strategies can be shared, misconceptions challenged and techniques refined.
Sandra C, London
I used this for a starter on one day, and on the following day, tackled percentages greater than 100% with a look at payday loans.
We also looked at the difference between interest rate p.a. and APR.
Mrs Boyce,
School starts for us here is just two short weeks, so I am excited to make Transum a part of that school day beyond just the starters! I would like to say one more thing...I truly appreciate you making the little buttons at the bottom of the page that change pounds to dollars and such! It is fun to have the students see and learn the symbol, and talk about how it works, and how it compares to US currency. Then it leads to discussion about money conversion from country to country.

Anyhow, I just wanted to take a moment and say well done! Your site is very well thought out. I appreciate your work very much.
Jenna T, Coorara Primary School.
These starters are really fun, our class does them every morning. This one was fun for our percentages, and I was the first to finish.

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.

Previous Day | This starter is for 26 August | Next Day

% - This is the percent symbol.
Percent means 'out of 100'.

Find 50%:

As 50 is half of 100, then 50% means half. To find 50% of a quantity you need to halve (or divide by two). So 50% of 6 is 3.

Find 10%:

As 10 is one tenth of 100, then 10% means 'one tenth of'. To find 10% of a quantity you need to divide it by ten. So 10% of 800 is 80.

Find 25%:

As 25 is one quarter of 100, then 25% means 'one quarter of'. To find 25% of a quantity you need to divide it by four. So 25% of 20 is 5.

Another way of finding 25% of a quantity is first finding 50% then dividing the result by 2.

Find 33⅓%:

As 33⅓ is one third of 100, then 33⅓% means 'one third of'. To find 33⅓% of a quantity you need to divide it by three. So 33⅓% of 30 is 10.

Find 1%:

As 1 is one hundredth of 100, then 1% means 'one hundredth of'. To find 1% of a quantity you need to divide it by 100. So 1% of 800 is 8.

Find other percentages:

Other percentages can be found by combining some of the techniques mentioned above. Here are some examples:

To find 75% of a quantity add together 50% and 25% of it.
To find 20% of a quantity double 10% of it.
To find 5% of a quantity halve 10% of it.
To find 66⅔% of a quantity double 33⅓% of it.
To find 90% of a quantity subtract 10% from it.
To find 80% of a quantity subtract 20% from it.
To find 2% of a quantity double 1% of it.
To find 52% of a quantity add 50% to 2% of it.

If you need to use a calculator to check your working. See Calculator Workout skill 3.

Commute

Did you know that if you are struggling to mentally work out 24% of 50 you can switch the numbers round and work out 50% of 24 instead. Finding 50% is very easy isn’t it? You will get the same answer.

Finding a percentage of a quantity is an example of a commutative calculation. Not all operations are commutative. Subtraction certainly isn’t as 10 minus one is not the same as one minus ten.

You can use this trick to improve your ability to do this type of calculation quickly if you find the switch makes it easier.

Practise with 12% of 50, 4% of 25 and 75% of 10.

Answers

Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.

Teacher, do your students have access to computers such as tablets, iPads or Laptops? This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments:

Transum.org/go/?Start=August26

However it would be better to assign one of the student interactive activities below.

Laptops In Lessons

Here is an interactive online exercise for pupils:

Transum.org/go/?to=UnitPricing

Curriculum Reference

See the National Curriculum page for links to related online activities and resources.