Think of a number

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Think of a number
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Think of a number between 10-50

• Double it

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• Add 6

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• Take 2

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Halve the number
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Take away the number you thought of
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Write down the number you are left with.
I think the number is..
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• 2

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That was clever wasnt it?
Lets try another one
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Think of an even number less than 50.
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• Halve it

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• Add 19

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Take away 9
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• Double

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• Take away the number you first thought of

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Write down the number you are left with.
I think the number is..
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• 20

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Plenary

• With a partner, discuss why the think a number
  puzzles always end up with the same number?
• Can you make up one of your own?

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