### Instruction: What is the least prime number which is the sum of two distinct positive perfect squares?### Response: To find the least prime number which is the sum of two distinct positive perfect squares, I need to consider the possible values of the perfect squares and check if their sum is prime.
Since the squares are distinct, I can assume that one of them is smaller than the other, and start from the smallest possible values.
The smallest perfect square is 1, so I can try 1 + another square and see if it is prime.
The next perfect square is 4, so I can try 1 + 4 = 5, which is prime.
Therefore, 5 is the least prime number which is the sum of two distinct positive perfect squares, and I don't need to check any larger squares.