Question 750116
{{{841}}} is close to and a  little less than {{{900=30^2}}}
{{{(30-x)^2=900-60x+x^2}}}
{{{x=1}}} makes {{{(30-x)^2=900-60*1+1^2=90-60+1=841}}}
so {{{841=(30-1)^2=29^2}}} and {{{sqrt(841)=29}}}
 
NOTE:
For other numbers, you could get at the answer by doing a prime factorization.