Conversor de temperatura!

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>

int main ()
{
   
    int opcao,novo=1;
    float grausC,grausF,grausK,grausR;
   
    do{
         
       do{
            
             printf("Este programa converte de graus celsios para Fahrenheit, Kelvin, Rankine\ne vice versa\n\n");
             printf("\nAperte <1> de celsius para fahrenheit");
             printf("\nAperte <2> de celsius para kelvin");
             printf("\nAperte <3> de celsius para rankine");
             printf("\nAperte <4> de fahrenheit para celsius");
             printf("\nAperte <5> de kelvin para celsius");
             printf("\nAperte <6> de rankine para celsius");
             printf("\nAperte <7> para encerrar\n");
             scanf("%d",&opcao);
             system("cls");
             }while((opcao<1)||(opcao>7));
                      
       switch(opcao)
       {
           case 1:
             printf ("Informe a temperatura em graus Celsius: \n");
             scanf ("%f",&grausC);
             grausF = (grausC*1.8)+32;
             printf ("Farenheit = %.2f",grausF);
             getch();
             system("cls");
             break;
            
           case 2:
             printf ("Informe a temperatura em graus Celsius: \n");
             scanf ("%f",&grausC);
             grausK= grausC+273.5;
             printf ("Kelvin = %.2f",grausK);
             getch();
             system("cls");
             break;
            
           case 3:
             printf ("Informe a temperatura em graus Celsius: \n");
             scanf ("%f",&grausC);
             grausR= (grausC* 1,8) + 32 + 459.67;
             printf ("Rankine = %.2f",grausR);
             getch();
             system("cls");
             break;
            
           case 4:
             printf ("Informe a temperatura em graus Fahrenheit: \n");
             scanf ("%f",&grausF);
             grausC = (grausF-32)/1.8;
             printf ("Celsius = %.2f",grausC);
             getch();
             system("cls");
             break;
            
           case 5:
             printf ("Informe a temperatura em graus kelvin: \n");
             scanf ("%f",&grausK);
             grausC = grausK-273.5;
             printf ("Celsius = %.2f",grausC);
             getch();
             system("cls");
             break;
            
           case 6:
             printf ("Informe a temperatura em graus Rankine: \n");
             scanf ("%f",&grausR);
             grausC = (grausR-32-459.67) / 1.8;
             printf ("Celsius = %.2f",grausC);
             getch();
             system("cls");
             break;
            
           case 7:
                novo=0;
                break;
        }
       
        }while(novo == 1 );
                     
     
        return(0);
}

//"cls" é para limpar a tela.

O link abaixo possui o executavel!

by  Wellington