How do we know that the value of Pi goes on forever?

Asked by: Tasha Ford, Warwick

The Swiss mathematician Johann Lambert proved this around 250 years ago by showing that Pi can’t be expressed exactly as the ratio of one number to another – in other words, it’s an ‘irrational’ number that goes on forever, never repeating itself. While we often use rational values for Pi like 22/7, these are only approximations to its true value, and always repeat after a certain number of decimal places.

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