### 9.5.05

## useless but cute

on sunday i learnt the proof that every prime number which is one more than a multiple of four can be expressed as the sum of two square numbers, and decided that this was probably the most practically useless piece of knowledge anyone could ever hope to know.

then i realised later that in fact, it could be very useful if you wanted to cut a piece of wood the same length as the square root of such a prime (using pythagoras)...

then i realised later that in fact, it could be very useful if you wanted to cut a piece of wood the same length as the square root of such a prime (using pythagoras)...