Wrong display when I have more than 9 chapters in ToC

Question

I'm in a really bad situation with my ToC in the book that I write. Everything is fine until the 9th chapter. There's the "9", some space and then the name of the chapter. But on the 10th (or more) chapter, the "1" of the "10" is under the "9". So the "0" of the "10" is where there should be a space. As a result, there is no space between the number of the chapter and the name of the chapter.

I expected that LaTeX would deal with it as it does with the bibliography entries. It leaves some space empty on the start of one digit numbers so they will be all aligned at the end. (For example, when we have [9] and [10], the 0 is under the 9)

Let me show you my preamble as well

\documentclass[12pt,a4paper]{book}
\usepackage[english, greek]{babel}
\usepackage[iso-8859-7]{inputenc}
\usepackage{kerkis}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{units}
\usepackage{array}
\usepackage{framed}
\usepackage{extarrows}
\usepackage[makeroom,Smaller]{cancel}
\usepackage[pdftex]{graphicx}
\usepackage[top=3.2cm, bottom=2.8cm, left=2.9cm, right=2.9cm,headsep=9mm]{geometry}
\usepackage[Bjornstrup]{fncychap}
\usepackage{fancybox}
\usepackage{fancyhdr}
\usepackage{colortbl}
\usepackage{xcolor}
\usepackage{footmisc}
\usepackage{subfiles}
\usepackage{float}
\usepackage{slashbox}
\usepackage[official]{eurosym}

(Here there are some commands but they've got nothing to do with that)

\begin {document}
\frontmatter
\tableofcontents
\newpage
\thispagestyle{empty}
\mbox{}
\newpage


\mainmatter
.
.
.

Answer 1

Use the tocloft package. Page 11 of its documentation describes how to set chapter resp. section numbers flushright.

\documentclass{book}

\usepackage{tocloft}
\newlength{\mylength}
\setlength{\mylength}{0.7em}
\renewcommand{\cftchappresnum}{\hfill}
\renewcommand{\cftchapaftersnum}{\hspace*{\mylength}}
\addtolength{\cftchapnumwidth}{\mylength}
\addtolength{\cftsecindent}{\mylength}
\addtolength{\cftsubsecindent}{\mylength}

\begin{document}

\tableofcontents

% The following code line is added to make the example truly minimal
\setcounter{chapter}{8} 

\chapter{Nine}

\chapter{Ten}

\section{Ten.One}

\subsection{Ten.One.One}

\end{document}