C :

#include<stdio.h>
int main()
{
	int n,i,s=1;
	scanf("%d",&n,1<=n,n<=10);
	for(i=1;i<=n;i++)
	{
		s=s*i;
	}
	printf("%d\n",s);
}

C++ :

#include<bits/stdc++.h> 
using namespace std;
int main()
{
	long long s=1;
	int n;
	cin>>n;
	for(int i=1;i<=n;++i)
	{
		s*=i;
		
	}
	cout<<s<<" "<<endl;
	return 0;
	
}

Java :

import java.util.Scanner;

/**
 * Hello world!
 *
 */
public class Main 
{
    public static void main( String[] args )
    {
        Scanner scanner = new Scanner(System.in);
        int i = scanner.nextInt();
        int a = 1;
        for (int i1 = 1; i1 <= i; i1++) {
            a *= i1;
        }
        System.out.println(a);
    }
}

Python :

# coding=utf-8
#!/usr/bin/python2
import sys
import re
import math


a= int(input())
sum=1
for i in range(1,a+1):
    sum=sum*i


print sum

C# :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    internal class Program
    {
        static void Main()
        {
            int num = 1;
            int n = Convert.ToInt32(Console.ReadLine());
            for (int i = 1; i <= n; i++)
            { num *= i; }
            Console.WriteLine(num); 
            Console.ReadKey();
     
        }
    }
}