If I would draw a right triangle with legs of length 1 centimeter with a ruler then its hypotenuse should be equal to $\sqrt2$ which is an irrational number - therefore its decimal representation, which is the limit of the sequence $\lim_{n \to\infty}\sum_{i=0}^\infty{\frac{a_i}{10^i}}$, has infinitely many numbers after the interger part of$ \sqrt2$.
What exactly can the ruler measure when drawing such a triangle, considering the fact that we draw irrational number (which by definition is infinitely long)?
I hope the question is clear.
Thanks.