C++ Programming Code Examples C++ > Mathematics Code Examples Program to find factorial of Number in C++ Program to find factorial of Number in C++ What is a Factorial of a number 'n'? The factorial of a number 'n' is the product of all number from 1 upto the number 'n' it is denoted by n!. For example n=5 then factorial of 5 will be 1*2*3*4*5= 120. 5!= 120 Factorial program C++ Logic: First think what is the factorial of a number? How mathematically it can be calculated. If you got this info then it will be very easier to make a C++ Program logic to find the factorial. User enters a number and we have to multiply all numbers upto entered number. Like if user enters 6 then Factorial should be equal to factorial= 1*2*3*4*5*6. In this case a for Loop will be very helpful. It will start from one and multiply all numbers upto entered number after it loop will be terminated. Take a variable and initialized it to 1 and in loop store multiplication result into it like in below program a variable Factorial is used for this purpose. what is we does not initialized it to 1 and initialized it to zero or remain it uninitialized. In case of 0 our result will be zero in case of any number entered In case of not initializing it our answer will correct mostly but if variable contains garbage value then we will not be able to get correct result. It is recommended that to initialize it to one. #include<iostream> using namespace std; int main() { int num,factorial=1; cout<<" Enter Number To Find Its Factorial: "; cin>>num; for(int a=1;a<=num;a++) { factorial=factorial*a; } cout<<"Factorial of Given Number is ="<<factorial<<endl; return 0; }