Question

What is the least 3 digit number that is the square of a prime number? 

a. 100
b. 109
c. 121
d. 125
e. 144

Answer

From the available  answer choices (a – e) above, consider:

100 = 10^2 = not a square of a prime number
109 = not a square
121 = 11^2 = a square of a prime number
125 = 5^3 = not a square
144 = 12^2 = not a square of a prime number

Hence answer is 11 since its the only square of a prime number in the list above. If you had more than one “square of prime number”, then you would have to choose the smallest so that we get the “least”.