How can you approximate the square root of 30

30 is between two perfect squares of 25 and 36 and so we can be sure that square root of 30 lies between 5 and 6 
Now the difference of 36 and 25 is 11.So we may say that for a difference of 11 units,there is a change of 1 in the value of the square rootl 
Now,find the difference of 30 and 25,the square of 25.It is 5 
So square root of 30 would be approaximately 5 plus 5/11 
or 5+0.455=5.46 approaximately

69 i think because is the only one square