Which of the following is a perfect square number?
9801
No perfect square ends with 2, 3 or 7 in their unit place.
9801 is the only option left.
On prime factorizing 9801, we will get
9801= 3 x3 x 3 x 3 x 11 x 11
3 and 11 both occur even number of times in the expansion of 9801.
Thus, 9801 is a perfect square with square root 99.