Calculator with switch statement

/********************************************************/
//Nicholas Tony Gomes
//Calculator with switch statement
//and functions
//2:15 pm oct 26 2017


#include <stdio.h>
#include <math.h>
void i_o();

double add(double x, double y)
{
    return x+y;
}
double sub(double x, double y)
{
    return x-y;
}
double multiply(double x, double y)
{
    return x*y;
}
double division(double x, double y)
{
    return x/y;
}
double remain(double x, double y)
{
    return fmod(x,y);
}
void i_o()
{
    printf("Press 1 for Addition\n");
    printf("Press 2 for Subtraction\n");
    printf("Press 3 for Multiply\n");
    printf("Press 4 for Division\n");
    printf("Press 5 for finding the Remainder\n");
}
int main()
{
    double num_input, num2_input;
    int num_operator,counter;

   for(counter=1;counter<=5;counter++){
    printf("\nEnter two numbers to calculate\n");
    scanf("%lf%lf",&num_input,&num2_input);
    i_o();
    scanf("%d",&num_operator);

    switch(num_operator)
    {
        case 1:
            printf("%.2lf",add(num_input,num2_input));
        break;

        case 2:
            printf("%.2lf",sub(num_input,num2_input));
        break;

        case 3:
            printf("%.2lf",multiply(num_input,num2_input));
        break;

        case 4:
            printf("%.2lf",division(num_input,num2_input));
        break;

        case 5:
            printf("%.2lf",remain(num_input,num2_input));
        break;


        default:
            printf("Wrong input!!!\n");
        break;
    }


    }
    return 0;
}