(add-to-list 'package-archives
    '("marmalade" .
      "http://marmalade-repo.org/packages/"))
(package-initialize)

(add-to-list 'package-archives
             '("melpa" . "http://melpa.org/packages/") t)

Opening TLS connection to `api.stackexchange.com'...done
if: Headers missing; response corrupt

\documentclass[10pt,notitlepage]{article}%

\usepackage{times}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}%
\usepackage{multicol}
\usepackage{hyperref}

%\let\ifloadgeometry\iffalse
%\input{commonlatex}
\usepackage[normalem]{ulem}
\usepackage[margin={3mm}]{geometry}%
\setlength{\columnsep}{3mm}
\setlength{\columnseprule}{.01pt} %thickness
\raggedcolumns

\begin{document}
\begin{multicols}{2}
%
\uline{Fourier Transform formulas}
\begin{align*}
\hat{u}(k)         & =  \int_{-\infty}^{\infty} u(x) e^{-i k x} \,dx \\

This is pdfTeX, Version 3.1415926-2.5-1.40.14 (MiKTeX 2.9 64-bit) (preloaded format=pdflatex 2014.2.24)  14 DEC 2014 13:25
entering extended mode
**p3.tex

(G:\nabbasi\data\nabbasi_web_Page\my_courses\univ_wisconsin_madison\fall_2014\m
ath_703_applied_math\cheat_sheet\p3.tex
LaTeX2e <2011/06/27>
Babel <v3.8m> and hyphenation patterns for english, afrikaans, ancientgreek, ar
abic, armenian, assamese, basque, bengali, bokmal, bulgarian, catalan, coptic,
croatian, czech, danish, dutch, esperanto, estonian, farsi, finnish, french, ga

>pdflatex p3.tex
This is pdfTeX, Version 3.14159265-2.6-1.40.15 (TeX Live 2014) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./p3.tex
LaTeX2e <2014/05/01>
Babel <3.9k> and hyphenation patterns for 78 languages loaded.
(/usr/local/texlive/2014/texmf-dist/tex/latex/base/article.cls
Document Class: article 2007/10/19 v1.4h Standard LaTeX document class
(/usr/local/texlive/2014/texmf-dist/tex/latex/base/size10.clo))
(/usr/local/texlive/2014/texmf-dist/tex/latex/psnfss/times.sty)

\documentclass{article}
\usepackage{tikz,xstring}

\begin{document}

\def\result{}
\foreach \i in {1,...,6}{%
  \let\phantom\relax
  \StrChar{12345}{\i}[\c]%
  \ifx\c\empty
    \def\c{\phantom{0}}%
  \fi
  \xdef\result{\result\c}}
\show\result

\stop