From Förberedande kurs i matematik 1

In the text, \displaystyle \sqrt{2} is given to \displaystyle 30 decimal places,

\displaystyle \sqrt{2}=1.414\ 213\ 562\ 373\ 095\ 048\ 801\ 688\ 724\ 210...\

and from this decimal expansion, we see that √2 to three decimal places is

\displaystyle \sqrt{2}=1.414

because the fourth decimal is 2 and is therefore rounded down.