math

sqrt(4761) = 69.

recheck: 69*69=sqrt(4761)

it is 69, to find it

$\sqrt{4761}= \sqrt{9*529}=3\sqrt{529}$

now, we know that 20 is close to 529 and only a units digit of 3 can result in a units digit of 9, so

$3\sqrt{529}=3\sqrt{23^2}=3*23=69$