Multiply, Add, Subtract and Divide

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
9, 8
13, 12
14, 10
13, 13
14, 15
17.5, 13
14.5, 14.5

No Calculator No Calculator No Calculator



At least one of your answers is wrong.


14 pounds = 1 stone.

You have won a stone!


There are plenty of stones around, take your pick.

A Mathematics Lesson Starter Of The Day

A Starter which is similar to this one but slightly easier is Multiply Sum by Difference then Divide.


Topics: Starter | Mental Methods

  • Louise, Brixham
  • The 14 pounds was a great motivator - after the lesson I discovered 14 pounds is a stone hahaha. I shall use this motivation again although obviously it will only work once with each group
    A good starter to get the kids working through all 4 rules of number
  • Tony Leach, Rickmansworth
  • Good challenge, and I am looking forward to receiving a heavy parcel soon!
  • Tom Lashland, Australia
  • Well, that was a surprise! I was thinking I could get easy cash but...
    I got a stone.
  • P McGinn, Kent
  • The "prize" joke at the end did not go down at all well ... for a difficult starter (that can take some time) seeing a joke when promised something else can take the wind out of the sails...
  • K. Wyman, Dorcehster Primary
  • The "prize" didn't go down well, especially as some children had worked really hard to solve each question.
  • Mr M, London
  • This was a very good starter, my class were very motivated and even calculated how much money they would each get. At the end when the stone came up they felt very disappointed but pleased with what they had achieved as a class.

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This starter has scored a mean of 3.0 out of 5 based on 273 votes.

Previous Day | This starter is for 27 June | Next Day



0.05 2.75 6.55 5.8
7.15 9.05 9.85 9.0625

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!


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