How shall i find the square root of 169 without using calculator? ? describe briefly..

Without experience that would help you recognize it right away, I think
you would just need to try numbers until you find it.

Pick a number, multiply it by itself with pencil and paper, and see if it works.

(2)² = 4     too small
(3)² = 9     too small, and not growing fast enough; this could take all day 
(10)² = 100    still too small
(15)² = 225    oops, too big; go back down
(12)² = 144    too small
(14)² = 196    too big
(13)² = 169    just right;  hope the bears don't come back too soon