3

How can we draw the ladder method for LCM (least common multiple) in LaTeX, as shown in the figure below,

enter image description here

If possible it'd be nice to have different colours for different lines and numbers, as shown

enter image description here

Note: I'd prefer to stick to amsmath or mathtools if possible.

2 Answers 2

6

Here's a solution that employs a two-column array environment. (LuaLaTeX is needed only for the calculation of the LCM as the product of the individual factors.)

enter image description here

\documentclass{article} 
\usepackage{colortbl} 

\begin{document}
\[
\setlength\extrarowheight{2pt}
\begin{array}{@{}l|l@{}}
2 & 48,72,108\\ \cline{2-2} 
2 & 24,36,54\\  \cline{2-2}
3 & 12,18,27\\  \cline{2-2}
\arrayrulecolor{red}
\color{red}3 & 4,6,9\\ \cline{2-2}
\color{red}2 & 4,2,3\\ \cline{2-2}
\multicolumn{1}{c}{} & 2,1,3
\end{array}
\]
The \textsc{lcm} of $48$, $72$, and $108$ is the product
$\verb|2*2*3*3*2*2*1*3|=\directlua{tex.sprint(2*2*3*3*2*2*1*3)}$.
\end{document}
5
  • No LuaLaTeX? ;-)
    – user31729
    Commented Dec 31, 2017 at 21:42
  • 2
    @ChristianHupfer - Happy New Year to you too!! :-)
    – Mico
    Commented Dec 31, 2017 at 23:18
  • Happy New Year!
    – user31729
    Commented Dec 31, 2017 at 23:49
  • 1
    @ChristianHupfer - You made me do it: I added a LuaLaTeX angle...
    – Mico
    Commented Jan 1, 2018 at 3:44
  • 1
    Sighhhhhhhhhhhhhhhhhh....
    – user31729
    Commented Jan 1, 2018 at 8:00
4

Most likely I do not understand your question correctly, but it seems to me that you want to color some elements of a table. If so, then you may start with this code.

\documentclass{article}
\usepackage{colortbl}
\usepackage[table]{xcolor}
\begin{document}
  \begin{tabular}{l|rrr}
   \rowcolor{red!40} 3  & 12 & 15 & 18\\
   \hline
   \rowcolor{blue!30} 2  & 4 & 5 & 6\\
   \hline
    &  2 & \textcolor{blue!70}{5} & 3
  \end{tabular}
\end{document}

enter image description here

To produce something along the lines of your second picture, you may try

\documentclass{article}
\usepackage{colortbl}
\usepackage[table]{xcolor}
\begin{document}
  \begin{tabular}{lrrr}
   \textcolor{red}{3}  & \multicolumn{1}{!{\color{red}\vline}r}{12} & 15 & 18\\
   \arrayrulecolor{red}\cline{2-4}
   \textcolor{red}{2} &    \multicolumn{1}{!{\color{red}\vline}r}{4} & 5 & 6\\
   \arrayrulecolor{red}\cline{2-4}
    &   2 & 5 & 3
  \end{tabular}
\end{document}

enter image description here

1
  • I have edited the original post. Hope it is clear now. pls check the second image.
    – Sooraj S
    Commented Dec 31, 2017 at 20:32

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .