make a calculator by function

#include<stdio.h>

float  add(float num1,float num2);
float  sub(float num1,float num2);
float  multiple(float num1,float num2);
float  division(float num1,float num2);
int  power(int num1);

int main()
{
   float n1,n2,result;
   scanf("%f %f",&n1,&n2);
   int option;
   scanf("%d",&option);
   switch(option)
   {
   case 1:
    result=add(n1,n2);
    printf("%f",result);
    break;
   case 2:
    result=sub(n1,n2);
    printf("%f",result);
    break;
    case 3:
    result=multiple(n1,n2);
    printf("%f",result);
    break;
  case 4:
    result=division(n1,n2);
    printf("%f",result);
    break;
  case 5:
    result=power(n1);
    printf("%f",result);
    break;
   }}
   float  add(float num1,float num2)
   {
       return num1+num2;

   }
    float  sub(float num1,float num2)
   {
       return num1-num2;

   }
    float  multiple(float num1,float num2)
   {
       return num1*num2;

   }

    float  division(float num1,float num2)
   {
       return num1/num2;

   }

 int power(int num1)
   {
       return pow(num1,2);

   }