Your Number Is...

'Your Number Is...' printed from https://nrich.maths.org/

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Press the button in the interactivity below, and see what happens:

Now try again starting with a different number.

Try again.

Try starting with a fraction... or decimal... or negative number...

Why are your answers ALWAYS the same?

Can you design instructions for similar "Think of a number" machines of your own?
Test them on a partner to check that they lead to your anticipated solutions.

You may want to take a look at Your Number Was... for a suitable follow-up activity.