[Tex/LaTex] Get chapter number

chaptersmemoirnumberingsectioning

I am newbie on latex, my question is how can I get a structure like:

number of chapter + title of chapter (exemple: I Introduction)
I only get Introduction, I want the number before the name.
If you can see the code , I apply a code which remove "Chapter x"
Code of tex file:

 \documentclass[11pt,a4paper,oldfontcommands,openany]{memoir}
 \usepackage[utf8]{inputenc}
 \usepackage[T1]{fontenc}
 \usepackage{microtype}
 \usepackage[dvips]{graphicx}
 \usepackage{xcolor}
 \usepackage{times}
 % Importation package use case  %
 \usepackage{tikz}
 \usepackage{tikz-uml} 
 \usepackage{amsmath}
 \usepackage{savetrees}
 %FIN IMPORTATION PACKAGE USECASE%
\usepackage[
breaklinks=true,colorlinks=true,
%linkcolor=blue,urlcolor=blue,citecolor=blue,% PDF VIEW
linkcolor=black,urlcolor=black,citecolor=black,% PRINT
bookmarks=true,bookmarksopenlevel=2]{hyperref}
\usepackage[export]{adjustbox}
\usepackage{geometry}
\usepackage[pagestyles]{titlesec}
\usepackage{etoolbox}

   % We remove chapter word {n}
  \titleformat{\chapter}[display]{\normalfont\bfseries}{}{0pt}{\Large}
  \newpagestyle{mystyle}
  {\sethead[\thepage][] [\chaptertitle]{}{}{\thepage}}
 \pagestyle{mystyle}
 %FIN IMPORT QUI ENLEVE CHAPTER 

 % PDF VIEW
 % \geometry{total={210mm,297mm},
 % left=25mm,right=25mm,%
 % bindingoffset=0mm, top=25mm,bottom=25mm}
 % PRINT
\geometry{total={210mm,297mm},
 left=20mm,right=20mm,
 bindingoffset=10mm, top=25mm,bottom=25mm}

           \OnehalfSpacing
          %\linespread{1.3}

           %%% CHAPTER'S STYLE
          %chapterstyle{bianchi}%
            %\chapterstyle{madsen}
          \chapterstyle{ell}
             %%% STYLE OF SECTIONS, SUBSECTIONS, AND SUBSUBSECTIONS
           \setsecheadstyle{\Large\bfseries\sffamily\raggedright}
          \setsubsecheadstyle{\large\bfseries\sffamily\raggedright}
       \setsubsubsecheadstyle{\bfseries\sffamily\raggedright}


             %%% STYLE OF PAGES NUMBERING
                %\pagestyle{companion}\nouppercaseheads 
              %\pagestyle{headings}
            %\pagestyle{Ruled}


               \maxsecnumdepth{subsection} % chapters, sections, and subsections are numbered
               \maxtocdepth{subsection} % chapters, sections, and subsections are in the Table of Contents



             \begin{document}

             %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---  % %%
             %   TITLEPAGE
             %

                   %   due to variety of titlepage schemes it is probably better to   make titlepage manually


                       \thispagestyle{empty}

            {%%%
            \sffamily
           \centering
          \Large

       ~\vspace{\fill}


      \clearpage
      \tableofcontents*



        \chapter*{Remerciements} this page is a sample page, not a chapter page      

        \chapter{Introduction} this is a chapter , I want the number before Introduction

Best Answer

use

\titleformat{\chapter}[display]{\normalfont\bfseries}{\thechapter}{0pt}{\Large}
                                                      ^^^^^^^^^^^^

or 

\titleformat{\chapter}[block]{\normalfont\bfseries}{\thechapter}{1em}{\Large}
                      ^^^^^^^^                      ^^^^^^^^^^^^  ^^^^

for " 1 title"

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