#Java 7, 116 76 bytes

int c(int i){int r=(int)Math.pow(10,(i+"").length())/9;return(-i/r-1)*-r-i;}

Used @Dennis' amazing approach to lower the byte-count by a whopping 40 bytes.

Ungolfed & test cases:

Try it here.

class Main{
  static int c(int i){
    int r = (int)Math.pow(10, (i+"").length()) / 9;
    return (-i / r - 1) * -r - i;
  }

  public static void main(String[] a){
    System.out.println(c(8));
    System.out.println(c(100));
    System.out.println(c(113));
    System.out.println(c(87654321));
    System.out.println(c(42));
    System.out.println(c(20000));
    System.out.println(c(11132));
  }
}

Output:

0
11
109
1234567
2
2222
11090

Java 7, 116 76 bytes

int c(int i){int r=(int)Math.pow(10,(i+"").length())/9;return(-i/r-1)*-r-i;}

Used @Dennis' amazing approach to lower the byte-count by a whopping 40 bytes.

Ungolfed & test cases:

Try it here.

class Main{
  static int c(int i){
    int r = (int)Math.pow(10, (i+"").length()) / 9;
    return (-i / r - 1) * -r - i;
  }

  public static void main(String[] a){
    System.out.println(c(8));
    System.out.println(c(100));
    System.out.println(c(113));
    System.out.println(c(87654321));
    System.out.println(c(42));
    System.out.println(c(20000));
    System.out.println(c(11132));
  }
}

Output:

0
11
109
1234567
2
2222
11090

#Java 7, 116 76 bytes

int c(int i){int r=(int)Math.pow(10,(i+"").length())/9;return(-i/r-1)*-r-i;}

Used @Dennis' amazing approach to lower the byte-count by a whopping 40 bytes.

Ungolfed & test cases:

Try it here.

class Main{
  static int c(int i){
    int r = (int)Math.pow(10, (i+"").length()) / 9;
    return (-i / r - 1) * -r - i;
  }

  public static void main(String[] a){
    System.out.println(c(8));
    System.out.println(c(100));
    System.out.println(c(113));
    System.out.println(c(87654321));
    System.out.println(c(42));
    System.out.println(c(20000));
    System.out.println(c(11132));
  }
}

Output:

0
11
109
1234567
2
2222
11090

#Java 7, 116 76 bytes

int c(int i){int r=(int)Math.pow(10,(i+"").length())/9;return(-i/r-1)*-r-i;}

Used @Dennis' amazing approach to lower the byte-count by a whopping 40 bytes.

Ungolfed & test cases:

Try it here.

class Main{
  static int c(int i){
    int r = (int)Math.pow(10, (i+"").length()) / 9;
    return (-i / r - 1) * -r - i;
  }

  public static void main(String[] a){
    System.out.println(c(8));
    System.out.println(c(100));
    System.out.println(c(113));
    System.out.println(c(87654321));
    System.out.println(c(42));
    System.out.println(c(20000));
    System.out.println(c(11132));
  }
}

Output:

0
11
109
1234567
2
2222
11090

#Java 7, 116 76 bytes

int c(int i){int r=(int)Math.pow(10,(i+"").length())/9;return(-i/r-1)*-r-i;}

Used @Dennis' amazing approach to lower the byte-count by a whopping 40 bytes.

Ungolfed & test cases:

Try it here.

class Main{
  static int c(int i){
    int r = (int)Math.pow(10, (i+"").length()) / 9;
    return (-i / r - 1) * -r - i;
  }

  public static void main(String[] a){
    System.out.println(c(8));
    System.out.println(c(100));
    System.out.println(c(113));
    System.out.println(c(87654321));
    System.out.println(c(42));
    System.out.println(c(20000));
    System.out.println(c(11132));
  }
}

Output:

0
11
109
1234567
2
222
11090

#Java 7, 116 76 bytes

int c(int i){int r=(int)Math.pow(10,(i+"").length())/9;return(-i/r-1)*-r-i;}

Used @Dennis' amazing approach to lower the byte-count by a whopping 40 bytes.

Ungolfed & test cases:

Try it here.

class Main{
  static int c(int i){
    int r = (int)Math.pow(10, (i+"").length()) / 9;
    return (-i / r - 1) * -r - i;
  }

  public static void main(String[] a){
    System.out.println(c(8));
    System.out.println(c(100));
    System.out.println(c(113));
    System.out.println(c(87654321));
    System.out.println(c(42));
    System.out.println(c(20000));
    System.out.println(c(11132));
  }
}

Output:

0
11
109
1234567
2
2222
11090