This is a difficult Starter so there is a prize if you can complete it. The prize fund currently stands at 14 pounds.
For each pair of numbers subtract the sum from the product then divide the result by 20 without using a calculator.
3, 2 
8, 7 
14, 13 
15, 16 
17, 11 
11, 16 
19.5, 15 
15.5, 15.5 
At least one of your answers is wrong.
Congratulations
14 pounds = 1 stone.
You have won a stone!
A Starter which is similar to this one but slightly easier is Multiply Sum by Difference then Divide.
Tweet about this starter  Share 
Topics: Starter  Mental Methods
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.
If you don't have the time to provide feedback we'd really appreciate it if you could give this page a score! We are constantly improving and adding to these starters so it would be really helpful to know which ones are most useful. Simply click on a button below:
This starter has scored a mean of 3.0 out of 5 based on 213 votes.
Previous Day  This starter is for 27 June  Next Day
0.05  2.05  7.75  10.45 
7.95  7.45  12.9  10.4625 
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.
Dividing by twenty is a lot to ask,
But an easier method will help you.
Dividing by ten is a much easier task,
Then divide your answer by two!
Casio Classwiz CalculatorThere is currently a lot of talk about this new calculator being the best in its price range for use in the Maths classroom. The new ClassWiz features a highresolution display making it easier to view numerical formulas and symbols but it isn't a graphical calculator as such (it has the capacity to draw graphs on your smart phone or tablet, via a scannable QR code and an app). As well as basic spreadsheet mode and an equation solving feature you also get the ability to solve quadratic, cubic or quartic polynomial inequalities and the answer is given just as it should be written down, using the correct inequality symbols! This calculator has a highperformance processor and twice the memory of previous models ensuring speedy operation and superior computational power.more... 
Teacher, do your students have
access to computers? 

Here a concise URL for a version of this page without the comments.
Here is the URL which will take them to a related student activity.