Square is that multiplication of number by itself. square root is opposite of square.
symbole of square is √ it is called radical
ex. take square of 4 is 16 [4*4=16] 
 square root of 4 is 2 [√4 = 2]
you can do with differant mathod like with calculator, by hand without calculator and square root alorithm [ you can use matlab for this also]
Square root of 1225 .place bar on every two digits here place bar on 12 and again on 25.then take the the perfect square like 3*3=9 it has to be taken here. why because if we take 4*4=16 this number is bigger than 12   

      3)1225(3  remainder here is 325 just carry down the 25  

next step double the digit 3(quotient) then we get 6 and multiply this with we have to place 5 after 6 which is divisor and also place this 5 after 3 in quotient sothat we can get the answer 35.i.e square root of 1225 is 35