### Explanation

The program prints all four-digit numbers which are perfect squares and where the first two digits and the last two digits are also perfect squares.

#### Header

The code begins with including the standard input-output header files using `#include <stdio.h>`

and `#include <math.h>`

for mathematical functions.

#### Program Description

The program prints a description message for the user to understand its functionality.

#### Perfect Square Calculation

The program finds and prints all special four-digit perfect square numbers using a `for`

loop:

`for (d = 1000; d <= 9999; d++)`

: Loops through each number from 1000 to 9999.`int m = sqrt(d);`

: Calculates the square root of the current number`d`

.`if (m * m == d)`

: Checks if the square of the square root is equal to the original number, indicating a perfect square.`int j = d / 100;`

: Extracts the first two digits of the number`d`

.`int o = d % 100;`

: Extracts the last two digits of the number`d`

.`int n = sqrt(j);`

: Calculates the square root of the first two digits.`int e = sqrt(o);`

: Calculates the square root of the last two digits.`if (n * n == j && e * e == o)`

: Checks if the first two digits and the last two digits are perfect squares.`printf("\t %d \t", d);`

: Prints the current number if it meets all the criteria.

#### Program End

The program ends with `printf("\n");`

to print a new line and `return 0;`

to indicate successful execution.

### Code

` ````
/*
* -----------------------------------------------------------
* Logic Building with Computer Programming (CSU1128)
* Instructor: Dr. Pankaj Vaidya | Author: Divya Mohan
*
* This code is a part of the educational initiative by dmj.one
* with aim of empowering and inspiring learners in the field of
* Computer Science and Engineering through the respective courses.
*
* (c) 2022, Divya Mohan for dmj.one. All rights reserved.
* -----------------------------------------------------------
*/
#include <stdio.h>
#include <math.h>
int main()
{
int d;
printf("\n\n Program to print all numbers which four digit perfect square and where");
printf("its first two digit and last two digits are also a perfect square. Example 1681. \n\n");
printf("All four digit special perfect square numbers between 1111 and 9999 are:\n");
for (d = 1000; d <= 9999; d++)
{
int m = sqrt(d); // Take root of i
if (m * m == d)
{
int j = d / 100;
int o = d % 100;
int n = sqrt(j);
int e = sqrt(o);
if (n * n == j && e * e == o)
{
printf("\t %d \t", d);
}
}
}
printf("\n");
return 0;
}
```

### Output

Program to print all numbers which four digit perfect square and where its first two digit and last two digits are also a perfect square. Example 1681.

All four digit special perfect square numbers between 1111 and 9999 are:

1600 1681 2500 3600 4900 6400 8100