C++ Programming Code Examples C++ > Mathematics Code Examples C++ Program to Find HCF of two numbers C++ Program to Find HCF of two numbers To find the HCF (Highest Common Factor) or GCD (Greatest Common Divisor) of two or more numbers, make prime factors of the numbers and choose the common prime factors. Then the take the highest common factor this highest common factor is HCF of number. For example; Suppose find HCF of 4 and 8 4=4*1=2*2 8=8*1=2*4=2*2*2 Factor of 4 is 1, 2, 4 Factor of 8 is 1, 2, 4, 8 So, common factor of 4 and 8 is 1, 2, 4 and highest common factor is 4 hcf of 4 and 8 is: 4 #include<iostream.h> #include<conio.h> void gcd(int,int); void main() { int a,b; clrscr(); cout<<"Enter two numbers: "; cin>>a>>b; gcd(a,b); getch(); // return 0; } //function to calculate g.c.d void gcd(int a,int b) { int m,n; m=a; n=b; while(m!=n) { if(m>n) m=m-n; else n=n-m; } cout<<"\nH.C.F of"<<a<<" & "<<b<<" is "<<m; }