**FOR MAKING SQUARE ROOT OF A NUMBER

this formula works when the main no is in between 10 to 99

for this we have to remember only ----

if the last digit of the given no is 0 then square root's last digit will be 0
if the last digit of the given no is 1 then square root's last digit will be 1 / 9
if the last digit of the given no is 4 then square root's last digit will be 2 / 8
if the last digit of the given no is 9 then square root's last digit will be 3 / 7 
if the last digit of the given no is 6 then square root's last digit will be 4 / 6
if the last digit of the given no is 5 then square root's last digit will be 5

and
1*2=2
2*3=6
3*4=12
4*5=20
5*6=30
6*7=42
7*8=56
8*9=72

RULE:-
if the given no is (ABCD) and its square root is (XY)      (A may be 0 or any digit)
then AB is near to (X*(X+1))
and Y can be determined by seeing D
if AB is just less than (X*(X+1)), then Y will be the lesser no
and
if AB is just bigger than (X*(X+1)), then Y will be the bigger no
 ...................................................................................................

EX:-
3969 is given
now 39 is just less than 6*7
so first digit of it's square root is 6
and as last digit of the given no is 9
so the last digit of it's square root will be either 3 or 7
now as 39 is less than 6*7
so last digit will be 3
so the ans is 63


784 is given
now 7 is just bigger than 2*3
so first digit of it's square root is2
and as last digit of the given no is 4
so the last digit of it's square root will be either 2 or 8
now as 39 is bigger than 6*7
so last digit will be 8
so the ans is 28