Of course it Pi – today is Pi day (March 14 @1.59 – get it?) – it’s also Einstein’s birthday.
An irrational number is one that can’t be expressed as a fraction (when expressed as a decimal it goes on for ever not recurring). Pi is often expressed as 22/7 but this is an approximation and not exact.
OK – my favourite Pi fact ..
If you were to wrap a piece of (non stretchable) string around the world tightly then raise it by 1 inch away from the earth all round, how much longer would the ‘1 inch off’ piece of string be (compared to the ‘tight’ string)?