Square numbers in that range are 625 and 676.
Sixteen of them.
16 prime numbers
The prime numbers between 700 and 800 are: 701 709 719 727 733 739 743 751 757 761 769.
The number halfway between them is 600.
400 to 500
You can find lists of prime numbers online in many places. Just search Google for "list of prime numbers" or something similar.
Square numbers in that range are 625 and 676.
Sixteen of them.
16 prime numbers
prime numbers from 300 to 700:307,311,313,317,331,337,347,349,353,359,367, 373,379,383,389,397,401,409,419,421,431,433, 439,443,449,457,461,463,467,479,487,491,499, 503,509,521,523,541,547,557,563,569,571,577, 587,593,599,601,607,613,617,619,631,641,643, 647,653,659,661,673,677,683,691
The prime numbers between 700 and 800 are: 701 709 719 727 733 739 743 751 757 761 769.
750
The number halfway between them is 600.
252 = 625
700
650