•  Program:

#include<stdio.h>
#include<conio.h>

int main()
{
int n,i,j,fact=1;
float sum=0;
printf("\n Enter Value of n : ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
    fact=1;
    for(j=i;j>0;j--)
    {
        fact=fact * j;
     }
    sum=sum+(1.0/fact);
}
printf("\n Sum of Series = %f",sum);
return 0;
}

 Enter Value of n : 6

 Sum of Series = 1.718055

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Sum of series = 1^2 + 2^2 + …. + n^2= n(n + 1)(2n + 1) / 6.

For loop is used to compute the sum of series. Initialize the value of ‘i’ variable as 1. Check the condition that the value of ‘i’ variable is less than or equal to the value of ‘number’ variable value. If the condition is true, then execute the iteration of the loop.

If-else condition statement is used to check that the value of ‘i’ variable is not equal to value of ‘number’ variable. If the condition is true, then execute the statement by only printing the value of ‘i’ variable. Otherwise, if the condition is false then execute the else statement and print the sum of series.

•  Program:

#include<stdio.h>
#include<conio.h>

int main()
{
    int i, n, a=0;
    printf("Enter a number : ");
    scanf("%d",&n);
    
    for(i=1;i<=n;i++)
    {
        a=a+(i*i);
    }
    printf("Evaluate series is : %d",a);
    getch();
}

Enter a number : 4
Evaluate series is : 30

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•  Program:

#include<stdio.h>
#include<conio.h>

int main() 
{
  int n, i, flag = 0;
  printf("Enter a positive integer: ");
  scanf("%d", &n);

  for (i = 2; i <= n / 2; ++i) 
  {
    if (n % i == 0) 
    {
      flag = 1;
      break;
    }
  }

  if (n == 1) 
  {
    printf("1 is neither prime nor composite.");
  } 
  else 
   {
    if (flag == 0)
       {
          printf("%d is a prime number.", n);
       }    
    else
       { 
          printf("%d is not a prime number.", n);
       }

   }
   getch();
   return 0;
}

Enter a positive integer: 56
56 is not a prime number.

• In the program, a for loop is iterated from 'i = 2' to 'i < n/2'
• In each iteration, whether 'n' is perfectly divisible by 'i' is checked using:

• If 'n' is perfectly divisible by 'i', 'n' is not a prime number.
• In this case, 'flag' is set to 1, and the loop is terminated using the 'break' statement.
• Notice that we have initialized 'flag' as 0 during the start of our program.
• So, if  'n' is a prime number after the loop, 'flag' will still be 0. However, if  'n' is a non-prime number, 'flag' will be 1. 

#include<stdio.h>
#include<conio.h>

int main()
{
 int person, height, weight, count=0;
 for(person=0;person<5;person++)
 {
  printf("\n Enter Detail of Person - %d",person+1);
  printf("\n Enter Height : ");
  scanf("%d",&height);
  printf("\n Enter Weight : ");
  scanf("%d",&weight);
  if(height>170)
  {
   if(weight<50)
   {
    count++;
   }
  }
 }
 printf("\n Total Person having Height > 170 and Weight < 50 : %d",count);
 return 0;
}

•  Output:

•  Program:

Enter 0 student marks
Enter marks :35
Enter marks :56
Enter marks :86
For student = 1
Total sum = 86
Total average = 43.000000
Enter 3 student marks
Enter marks :23
Enter marks :43
Enter marks :21
For student = 4
Total sum = 21
Total average = 4.200000

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•  Program:

#include<stdio.h>
#include<conio.h>

int main()
{
    int a, b=0, i=0, value;
    printf("Enter a number :");
    scanf("%d", &a);
    while(i<a)
    {
        printf("Enter number [%d] :",i+1);
        scanf("%d",&value);
        b=b+value;
        i++;
    }
    printf("Total sum = %d\n",b);
    printf("Total average marks = %f",((float)b/a));
    getch();
    return 0;
}

Enter a number :5
Enter number [1] :47
Enter number [2] :85  
Enter number [3] :26
Enter number [4] :96
Enter number [5] :18
Total sum = 272
Total average marks = 54.400000

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Write a C program to find product of digits of a number using while loop.
Write a C program in C to multiply the digits of a number.

In this blog post, we learn how to write a C Program to find sum of first and last digit of a number?. We will write the C program to find sum of first and last digit of a number using the Arithmetic Operators. Here we will calculate the sum of first and last digit of a number using the loop and without using the loop. Let see an example,

•  Program:

#include<stdio.h>
#include<conio.h>

int main()
{
    int num, sum=0, Firstdigit, Lastdigit;

    printf("Enter any number : ");
    scanf("%d",&num);

    Lastdigit = num % 10;
    Firstdigit = num;

    while(num >= 10)
    {
        num = num / 10;
    }
    Firstdigit = num;
    sum = Firstdigit + Lastdigit;

    printf("Sum of first and last digit : %d", sum);

    return 0;
}

Enter any number : 2463
Sum of first and last digit : 5

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