1 + 4 - 9 + 16 + ......................+ n²

//1 + 4 - 9 + 16 - 25 + 36 + ......................+ n²
Program:

#include<stdio.h>
int main()
{
int n,i,sum=1,sign=1;
printf("Enter n: ");
scanf("%d",&n);
for(i=2;i<=n;i++)
{
sum=sum+(i*i)*sign;
sign=sign*(-1);
}
printf("sum= %d",sum);
return 0;
}

Output:

1 - 1/4 + 1/9 - 1/16 + ................. + 1/n²

// 1 - 1/4 + 1/9 - 1/16 + ................. + 1/n²
Program:
#include<stdio.h>
int main()
{
int n,i,sign=1;
float sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+(1.0/(i*i))*(sign);
sign=sign*(-1);
}
printf("sum= %f",sum);
return 0;

}

Output:

1 + 1/4 + 1/9 + 1/16 + ..............+ 1/n²

//1 + 1/4 + 1/9 + 1/16 + ..............+ 1/n²
Program:

#include<stdio.h>
int main()
{
int n,i;
float sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+1.0/(i*i);
}
printf("sum= %f",sum);
return 0;
}

Output:

1 + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n)

// 1 + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n)
Program:

#include<stdio.h>
int main()
{
int n,i,j,sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
for(j=1;j<=i;j++)
{
sum=sum+j;
}
}
printf("sum= %d",sum);
return 0;
}

Output:

1 + 2 + 4 + 8 +................+ n

//1 + 2 + 4 + 8 + 16 + 32 +................+ n
Program:

#include<stdio.h>
int main()
{
int n,i,sum=0,k=1;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+k;
k=k*2;
}
printf("sum= %d",sum);
return 0;
}

Output:

1/1! + 1/2! + 1/3! +...............+ 1/n!

// 1/1! + 1/2! + 1/3! +...............+ 1/n!
Program:

#include<stdio.h>
int main()
{
int n,i,j,fact=1;
float sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
fact=1;
for(j=1;j<=i;j++)
{
fact=fact*j;
}
sum=sum+(1.0/fact);
}
printf("sum= %f",sum);
return 0;
}

Output:

1! + 2!+ 3!+...............+ n!

// 1! + 2!+ 3!+...............+ n!
Program:

#include<stdio.h>
int main()
{
int n,i,sum=0,k=1;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
k=k*i;
sum=sum+k;
}
printf("sum= %d",sum);
return 0;

}

Output:

1³ + 2³ + 3³ +..............+ n³

// 1³ + 2³ + 3³ +..............+ n³
Program:

#include<stdio.h>
int main()
{
int n,i,sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+(i*i*i);
}
printf("sum= %d",sum);
return 0;
}

Output:

1² + 2² +3² +.............+ n²

//1² + 2² +3² +.............+ n²
Program:

#include<stdio.h>
int main()
{
int n,i,sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+(i*i);
}
printf("sum= %d",sum);
return 0;

}

Output:

1+2+3+..............+n

//1+2+3+..............+n
Program:

#include<stdio.h>
int main()
{
int n,i,sum=0;
printf("Enter n: ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+i;
}
printf("sum= %d",sum);
return 0;
}

Output: