using System;

class working {

// question 1

  public static int Length(int num){

      return Length(num,0);} 

  public static int Length(int num, int numbers){

      if(num==0){

          return numbers;

      }

      return Length(num/10,numbers+1);

  }

//question 2

    public static int check(int num){

      return check(num,0);

  } 

  public static int check(int num, int number){

      if(num==0){

          return number;

      }

      if(num%2==0){

          number++;

      }

      return check(num/10,number);

  }

//question 3

   public static int over(int numbers){

       if(numbers/10%10==0){

           return numbers;

       }

      return over(numbers/10);

   }

//question 4

   public static bool look(int numbers, int find){

      if(numbers%10==find){ 

           return true;

      }

      if(numbers==0||find==0){ 

          return false;

      }

​

      return look(numbers/10, find);

   }

//question 5

   public static int devide(int num, int numbers){

       if(num<0||numbers==0){ 

           return 0;

       }  

       return devide(num, numbers, 0);

   }

   public static int devide(int num, int numbers, int counter){

       if(num-numbers>=0){

           return devide(num-numbers, numbers, counter)+1; 

       }

       return counter; 

   }

//question 6

   public static int think(int num, int numbers){

       if(num<=numbers){ 

           return 0;

       }  

       if(num-numbers>numbers){

           return think(num-numbers, numbers);

       }

       return num-numbers; 

   }

//question 7

  public static bool even_odd(int num){

       if(num/10%2!=num%10%2){  

         return false;

        }

       if(num<10){  

         return true;

       }  

       return even_odd(num/10);

   }

//question 9

  public static bool prime_number(int num){

        if (num <= 3){

            return true; 

        }

        if (num <= 1){

            return false; 

        }

        return prime_number(num, 2); 

    }

​

   public static bool prime_number(int num, int func){

        if (num % func == 0)

        {

            return false; 

        }

        if (func * func > num)

        {

                return true; 

        }

        return prime_number(num, func+1); 

}

  static void Main() {

  }

}

​

​