NRICH: Your Number Is...

Think of a number and follow the machine’s instructions… I know what your number is! Can you explain how I know?

Age 7 to 14

Press the button in the interactivity  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.

Algebra & Pre-Algebra, Linear Equations, Quadratic Equations
K-6, Middle School, High School, Educator

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NRICH (University of Cambridge)

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Online Interactive Activity

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