wont work):

[Nerodic]

#include <iostream>
#include <string>
#include <Windows.h>
#include <cmath>
using namespace std;

int main()
{
std::string input;
cout << "Choose arithmetic: Addition or Subtraction or Multiply or Divison " << endl;
cin >> input;

if(input == "Addition")
{
int first;
cout << "Enter the first number: " ;
cin >> first ;

int second;
cout << "Enter the second number: " ;
cin >> second ;

int sum = first + second;
cout << "The sum of these numbers is: " << sum << '\n' ;
Sleep(20000);
}

if(input == "Subtraction")
{
int first;
cout << "Enter the first number: " ;
cin >> first ;

int second;
cout << "Enter the second number: " ;
cin >> second ;

int diff = first - second;
cout << "The difference of these numbers is: " << diff << '\n' ;
Sleep(20000);

}
if(input=="Multipy")
{
int first;
cout << "Enter the first number: " ;
cin >> first;

int second;
cout << "Enter the second number: ";
cin >> second;

int diff = first * second;
cout << "The difference of these numbers is: " << diff << '\n' ;
Sleep(200000);
}

if(input=="Divison")
{
int first;
cout << "Enter the first number: " ;
cin >> first;

int second;
cout << "Enter the second number: ";
cin >> second;

int d = first / second;
cout << "The difference of these numbers is: " << d << endl;
Sleep(20000);
}
}

[firedraco]

What do you mean?

[Uk Marine]

ehh... i'm not gonna read that, please choose the source code format.

[jwkNwA7f]

Please use code tags: http://www.cplusplus.com/articles/jEywvCM9/

I don't see any problems right off, except
Since you have already done: using namespace std; , then this line:
std::string input;
should be:
string input;

[flony1]

I would modify this part

std::string input;
cout << "Choose arithmetic: Addition or Subtraction or Multiply or Divison " << endl;
cin >> input;

by this other

string input;
cout << "Choose arithmetic: Addition or Subtraction or Multiply or Divison " << endl;
getline(cin, input);

as you use it, erase
#include<cmath>