Q:

Kaktovik inupiaq numerals

How can I insert these numeral symbols

in LaTeX? Are these available via some package?

A:

You could build them with TikZ, see here for a discussion. TikZ does not only allow us to draw these things, but it also comes with all the means to do the modulo arithmetic to make this enterprise a bit enjoyable. (One could make it much more "interesting" and shorter using tricks like the turtle library. However, this post is to give you a start without these gimmicks.) This implements the numbers 1-20. Their font size and weight adjusts itself to the surrounding.
\documentclass{article}
\usepackage{scalerel}
\usepackage{tikz}
\makeatletter
\DeclareRobustCommand{\checkbold}[1]{% https://tex.stackexchange.com/a/24635/121799
 \edef\@tempa{\math@version}\edef\@tempb{bold}%
 \ifx\@tempa\@tempb%
  \def#1{1}%
 \else
  \def#1{0}%
 \fi}
\makeatother 
\tikzset{pics/InupiaqNo/.cd,
1/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.5ex,0);}},
2/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.4ex,0)-- (0.8ex,1ex);}},
3/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.3ex,0)-- (0.6ex,1ex) -- (0.9ex,0ex);}},
4/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.25ex,0)-- (0.5ex,1ex) -- (0.75ex,0ex)-- (1ex,1ex) ;}},
5/.style={code={\draw (0,0) -- (1ex,0.4ex);}},
10/.style={code={\draw (0,0) -- (1ex,0.3ex) -- (0,0.6ex);}},
15/.style={code={\draw (0,0) -- (1ex,0.25ex) -- (0,0.5ex) --(1ex,0.75ex);}},
}
\newcommand{\InupiaqNo}[2][]{\checkbold\tmp%
\scalerel*{%
\begin{tikzpicture}[baseline=0em,line width={(1+0.45*\tmp)*0.06em},
    line cap=round,line join=round,#1]
\ifnum#2>0
 \ifnum#2<21
  \ifnum#2=20
   \draw[looseness=1.6] (0,1ex) to[out=-45,in=0] (0.5ex,0) to[out=180,in=-135] (1ex,1ex);
   \path (0,0) (1ex,2ex);
  \else 
   \pgfmathtruncatemacro{\SingleDigits}{Mod(#2,5)}%
   \pgfmathtruncatemacro{\FiveDigits}{int(#2/5)*5}%
   \path \ifnum\SingleDigits=0 \else pic{InupiaqNo/\SingleDigits} \fi
   \ifnum\FiveDigits=0 \else (0,1.2ex) pic{InupiaqNo/\FiveDigits} \fi
    (0,0) (1ex,2ex);
  \fi   
 \fi
\fi
\end{tikzpicture}}{M}%
}
\begin{document}
\foreach \X [evaluate=\X as \Y using {int(\X+10)}] in {1,...,10}
{$\X:~\InupiaqNo{\X}\ifnum\X=10 \quad~\,\else\qquad\fi\Y:~\InupiaqNo{\Y}$\par}

{\Large $12:~\InupiaqNo{12}$} {\Large\boldmath $12:~\InupiaqNo{12}$} 
{\Huge $7:~\InupiaqNo{7}$} {\Huge\boldmath $17:~\InupiaqNo{17}$}
\end{document}

EDIT: Made them single-stroke characters, thanks to @DavidCarlisle for reminding me. 
It might be just me but somehow these symbols remind me of something...
\documentclass{article}
\usepackage{scalerel}
\usepackage{tikz}
\makeatletter
\DeclareRobustCommand{\checkbold}[1]{% https://tex.stackexchange.com/a/24635/121799
 \edef\@tempa{\math@version}\edef\@tempb{bold}%
 \ifx\@tempa\@tempb%
  \def#1{1}%
 \else
  \def#1{0}%
 \fi}
\makeatother 
\tikzset{pics/InupiaqNo/.cd,
1/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.5ex,0);}},
2/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.4ex,0)-- (0.8ex,1ex);}},
3/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.3ex,0)-- (0.6ex,1ex) -- (0.9ex,0ex);}},
4/.style={code={\draw \ifnum\FiveDigits>0 (0,1.2ex) \else (0,1ex)\fi -- (0.25ex,0)-- (0.5ex,1ex) -- (0.75ex,0ex)-- (1ex,1ex) ;}},
5/.style={code={\draw (0,0) -- (1ex,0.4ex);}},
10/.style={code={\draw (0,0) -- (1ex,0.3ex) -- (0,0.6ex);}},
15/.style={code={\draw (0,0) -- (1ex,0.25ex) -- (0,0.5ex) --(1ex,0.75ex);}},
}
\newcommand{\InupiaqNo}[2][]{\checkbold\tmp%
\scalerel*{%
\begin{tikzpicture}[baseline=0em,line width={(1+0.45*\tmp)*0.06em},
    line cap=round,line join=round,#1]
\ifnum#2>0
 \ifnum#2<21
  \ifnum#2=20
   \draw[looseness=1.6] (0,1ex) to[out=-45,in=0] (0.5ex,0) to[out=180,in=-135] (1ex,1ex);
   \path (0,0) (1ex,2ex);
  \else 
   \pgfmathtruncatemacro{\SingleDigits}{Mod(#2,5)}%
   \pgfmathtruncatemacro{\FiveDigits}{int(#2/5)*5}%
   \path \ifnum\SingleDigits=0 \else pic{InupiaqNo/\SingleDigits} \fi
   \ifnum\FiveDigits=0 \else (0,1.2ex) pic{InupiaqNo/\FiveDigits} \fi
    (0,0) (1ex,2ex);
  \fi   
 \fi
\fi
\end{tikzpicture}}{M}%
}
\begin{document}
\Huge\noindent\pagecolor{black}\color{green}\foreach \X in {1,...,496}
{\pgfmathtruncatemacro{\myrnd}{1+20*rnd}\InupiaqNo{\myrnd}\space}

\end{document}

ADDENDUM: Just for fun: played a bit with the cool calligraphy library. There is a lot room for improvement (on my side, of course) but this was just to try out things. It also stores the characters in saveboxes which is advantageous if you use lots of them.
\documentclass{article}
\usepackage{scalerel}
\usepackage{tikz}
\usetikzlibrary{calligraphy}
\tikzset{pics/InupiaqNo/.cd,
1/.style={code={\calligraphy \ifnum\FiveDigits=0 (0,1ex) \else (0,1.2ex)\fi to[bend right=10]  (0.5ex,0);}},
2/.style={code={\calligraphy \ifnum\FiveDigits=0 (0,1ex) \else (0,1.2ex)\fi
to[bend right=10] (0.4ex,0) to[bend left=10] (0.8ex,1ex);}},
3/.style={code={\calligraphy \ifnum\FiveDigits=0 (0,1ex) \else (0,1.2ex)\fi
to[bend right=10] (0.3ex,0) to[bend left=10] (0.6ex,1ex) to[bend right=10] (0.9ex,0ex);}},
4/.style={code={\calligraphy \ifnum\FiveDigits=0 (0,1ex) \else (0,1.2ex)\fi
to[bend right=10] (0.25ex,0) to[bend left=10] (0.5ex,1ex) to[bend right=10]
(0.75ex,0ex) to[bend left=10] (1ex,1ex) ;}},
5/.style={code={\calligraphy (0,0) to[bend right=10] (1ex,0.4ex);}},
10/.style={code={\calligraphy (0,0) to[bend right=10] (1ex,0.3ex) to[bend
left=10] (0,0.6ex);}},
15/.style={code={\calligraphy (1ex,0.75ex) to[bend left=10] (0,0.5ex)
 to[bend right=10] (1ex,0.25ex) to[bend left=10] (0,0);}},
}
\newcommand{\InupiaqNoTikZ}[2][]{%
\begin{tikzpicture}[baseline=0em,#1]
\ifnum#2>0
 \ifnum#2<21
  \ifnum#2=20
   \pen (-90:{0.06ex})  -- (90:{0.06ex});
   \calligraphy[light,looseness=1.6] (0,1ex) to[out=-45,in=0] (0.5ex,0) to[out=180,in=-135] (1ex,1ex);
   \path (0,0) (1ex,2ex);
  \else 
   \pgfmathtruncatemacro{\SingleDigits}{Mod(#2,5)}%
   \pgfmathtruncatemacro{\FiveDigits}{int(#2/5)*5}%
   \pen (-95:{0.08em})  -- (85:{0.08em});
   \path \ifnum\SingleDigits=0 \else pic{InupiaqNo/\SingleDigits} \fi;
   \pen (-180:{0.08em}) -- (0:{0.08em});
   \path \ifnum\FiveDigits=0 \else (0.08ex,1.28ex) pic{InupiaqNo/\FiveDigits} \fi
    (0,0) (1ex,2ex);
   \ifnum\the\numexpr\SingleDigits*\FiveDigits>0
   \fi
  \fi   
 \fi
\fi
\end{tikzpicture}}
\foreach \X in {1,...,20}
{\expandafter\newsavebox\csname InupiaqBox\X\endcsname
\global\expandafter\sbox\csname InupiaqBox\X\endcsname{\InupiaqNoTikZ{\X}}}

\newcommand{\InupiaqNo}[1]{\scalerel*{\expandafter\usebox\csname InupiaqBox#1\endcsname}{M}%
}
\begin{document}
\Huge
\foreach \X in {1,...,20} {\X:\InupiaqNo{\X}\space}
\end{document}

