65. Program to accept two integer numbers and print the GCD(Greatest Common Divisor).

#include<stdio.h>
#include<conio.h>
void main()
{
int x, y, m, i;
clrscr();
printf("Enter 1st number : ");
scanf("%d", &x);
printf("Enter 2nd number : ");
scanf("%d", &y);

if (x > y)
m = y;
else
m = x;

for (i = m; i >= 1; i--)
{
if (x % i == 0 && y % i == 0)
{
printf("GCD of two number is : %d", i);
break;
}
}
getch();
}
@C_Codings

66. Program to find power of number.

#include<stdio.h>
#include<conio.h>
void main()
{
int base, expo;
int value = 1;
clrscr();
printf("Enter base number : ");
scanf("%d", &base);
printf("Enter exponent number : ");
scanf("%d", &expo);

while (expo != 0)
{
// value = value * base;
value *= base;
--expo;
}
printf("Answer : %d", value);
getch();
}
@C_Codings

67. Program to calculate HCF & LCM.

#include<stdio.h>
#include<conio.h>
void main()
{
int a, b, x, y, t, hcf, lcm;
clrscr();
printf("Enter two numbers : ");
scanf("%d%d", &x, &y);

a = x;
b = y;

while (b != 0)
{
t = b;
b = a % b;
a = t;
}

hcf = a;
lcm = (x * y) / hcf;

printf("\nHighest Common Factor of %d and %d : %d", x, y, hcf);
printf("\nLeast Common Multiple of %d and %d : %d", x, y, lcm);
getch();
}
@C_Codings

68. Program to find largest among 3 numbers using ternary operator.

#include<stdio.h>
#include<conio.h>
void main()
{
int a, b, c, big;
clrscr();
printf("Enter 3 numbers : ");
scanf("%d %d %d", &a, &b, &c);

big = (a > b && a > c ? a : b > c ? b : c);
printf("\nThe biggest number is : %d", big);
getch();
}
@C_Codings

69. Program to find largest number of 'n' numbers.

#include<stdio.h>
#include<conio.h>
void main()
{
int n, num, i;
int big;
clrscr();
printf("Enter total numbers : ");
scanf("%d", &n);

printf("Number %d : ", 1);
scanf("%d", &big);

for (i = 2; i <= n; i++)
{
printf("Number %d : ", i);
scanf("%d", &num);

if (big < num)
big = num;
}

printf("Largest number is : %d", big);
getch();
}
@C_Codings

70. Program to check whether the number is neon number or not.

#include<stdio.h>
#include<conio.h>
void main()
{
int n, sq, i, sum = 0;
clrscr();
printf("Enter the number : ");
scanf("%d", &n);

sq = n * n;

for (i = sq; i > 0; i = i / 10)
sum = sum + i % 10;

if (sum == n)
printf("%d is a neon number.", n);
else
printf("%d is not a neon number.", n);
getch();
}
@C_Codings

71. Program to check Niven number (Harshad number).

#include<stdio.h>
#include<conio.h>
void main()
{
int n, d, a, sum = 0;
clrscr();
printf("Enter the number : ");
scanf("%d", &n);

a = n;

while (a > 0)
{
d = a % 10;
sum = sum + d;
a = a / 10;
}

if (n % sum == 0)
printf("\nThe number is Niven Number.");
else
printf("\nThe number is not a Niven Number.");
getch();
}
@C_Codings

72. Program to check whether the number is palindrome or not.

#include<stdio.h>
#include<conio.h>
void main()
{
int n, rev = 0, temp;
clrscr();
printf("Enter a number : ");
scanf("%d", &n);

temp = n;

while (temp != 0)
{
rev = rev * 10;
rev = rev + temp % 10;
temp = temp / 10;
}

if (n == rev)
printf("\n%d is palindrome number.", n);
else
printf("\n%d is not palindrome number.", n);
getch();
}
@C_Codings

73. Program to check perfect number.

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

void main()
{
int n, i = 1, sum = 0;
clrscr();
printf("Enter a number : ");
scanf("%d", &n);

/*The first perfect number is 6, because 1, 2, and 3 are its proper positive divisors, and 1 + 2 + 3 = 6.*/

while (i < n)
{
if (n % i == 0)
{
sum = sum + i;
}
i++;
}

if (sum == n)
{
printf("\n%d is a perfect number.", i);
}
else
{
printf("\n%d is not a perfect number.", i);
}
getch();
}
@C_Codings

74. Program to find the square root of a number.

#include<math.h>
#include<stdio.h>
#include<conio.h>
void main()
{
double num, result;
clrscr();
printf("Enter number : ");
scanf("%lf", &num);
result = sqrt(num);
printf("Square root of %lf is %lf.", num, result);
getch();
}
@C_Codings

75. Program to print sum of 'n' prime numbers.

#include<stdio.h>
#include<conio.h>
void main()
{
int n, i = 3, count, c, sum = 2;
clrscr();
printf("Enter total number of prime numbers for addition : ");
scanf("%d", &n);

if (n >= 1)
{
printf("\nFirst %d prime numbers are :", n);
printf("\n2 ");
}
for (count = 2; count <= n;)
{
for (c = 2; c <= i - 1; c++)
{
if (i % c == 0)
break;
}
if (c == i)
{
sum = sum + i;
printf("%d ", i);
count++;
}
i++;
}
printf("\nSum : %d", sum);
getch();
}
@C_Codings

76. Program to print sum of factorial series 1/1! + 2/2! +...1/N!

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

double sumseries(double);

void main()
{
double number, sum;
clrscr();

printf("Enter the number : ");
scanf("%lf", &number);
sum = sumseries(number);

printf("\nSum of the above series = %lf ", sum);

getch();
}

double sumseries(double m)
{
double sum2 = 0, f = 1, i;
for (i = 1; i <= m; i++)
{
f = f * i;
sum2 = sum2 + (i / f);

if (i == m)
{
printf("%.2lf / %.2lf = %lf", i, f, sum2);
}
else
{
printf("%.2lf / %.2lf + \n", i, f);
}
}
return(sum2);
}
@C_Codings

77. Program to calculate the sum of 'n' terms in Taylor series.

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

void main()
{
int x, i;
int fact = 1, n;
float sum = 0;
clrscr();
printf("Enter the value of x : ");
scanf("%d", &x);
printf("Enter the number of terms : ");
scanf("%d", &n);

for (i = 1; i < n; i++)
{
fact = fact * i;
sum = sum + (pow(x, i) / fact);
}
sum = sum + 1;
printf("The sum of taylor series is : ");
printf("%f", sum);
getch();
}
@C_Codings

78. Program to swap two numbers without using third variable.

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

void main()
{
int x = 10, y = 5;
clrscr();
printf("Enter x : ");
scanf("%d", &x);
printf("Enter y : ");
scanf("%d", &y);

printf("\nBefore Swapping : \n x = %d \n y = %d", x, y);

// Code to swap x and y
x = x + y;
y = x - y;
x = x - y;

printf("\nAfter Swapping : \n x = %d \n y = %d", x, y);
getch();
}
@C_Codings

79. Program to swap two numbers using bitwise XOR.

#include<stdio.h>
#include<conio.h>
void main()
{
long i, k;
clrscr();
printf("Enter two integers : \n");
scanf("%ld %ld", &i, &k);

printf("\n Before swapping i : %ld and k : %ld", i, k);
i = i ^ k;
k = i ^ k;
i = i ^ k;
printf("\nAfter swapping i : %ld and k : %ld", i, k);
getch();
}
@C_Codings

80. Program to swap two numbers using pointer.

#include<stdio.h>
#include<conio.h>
void main()
{
int a, b;
int *ptra, *ptrb, *temp;
clrscr();
printf("Enter a : ");
scanf("%d", &a);
printf("Enter b : ");
scanf("%d", &b);

printf("\nBefore swapping : a : %d, b : %d", a, b);

ptra = &a;
ptrb = &b;

temp = ptra;
*ptra = *ptrb;
*ptrb = *temp;

printf("\nAfter swapping : a : %d, b : %d", a, b);
getch();
}
@C_Codings

81. Program to add two numbers using pointer.

#include<stdio.h>
#include<conio.h>
void main()
{
int first, second, *p, *q, sum;
clrscr();
printf("Enter two integers : \n");
scanf("%d %d", &first, &second);

p = &first;
q = &second;

sum = *p + *q;

printf("\nSum of entered numbers : %d", sum);
getch();
}
@C_Codings

82. Program to add first and last digit of a number.

#include<stdio.h>
#include<conio.h>
void main()
{
int input, firstNum, lastNum;
clrscr();

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

lastNum = input % 10;
firstNum = input;

while (firstNum >= 10)
firstNum /= 10;

printf("\nAddition of first and last number : %d + %d = %d",
firstNum, lastNum, firstNum + lastNum);
getch();
}
@C_Codings

83. Program to find area of triangle using Heron's formula.

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

void main()
{
double a, b, c, s, area;
clrscr();
printf("\nEnter the sides of triangle : \n");
scanf("%lf%lf%lf", &a, &b, &c);

s = (a + b + c) / 2;
area = sqrt(s * (s - a) * (s - b) * (s - c));

printf("\nArea of triangle using Heron's Formula : %.2lf", area);
getch();
}
@C_Codings

84. Program to convert Binary to Decimal.

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

int binary_decimal(int n);

void main()
{
int n;
char c;
clrscr();
printf("Enter Binary number : ");
scanf("%d", &n);
printf("%d in binary = %d in decimal", n, binary_decimal(n));
getch();
}

//Function to convert binary to decimal.

int binary_decimal(int n)
{
int decimal = 0, i = 0, rem;
while (n != 0)
{
rem = n % 10;
n /= 10;
decimal += rem * pow(2, i);
++i;
}
return decimal;
}
@C_Codings