\documentclass[]{exam}  % use the 'answer' option to compile solutions
\usepackage{subfiles}
\usepackage[utf8]{inputenc}
\usepackage{lastpage}
\usepackage[american,siunitx]{circuitikz}
\sisetup{detect-all}
\begin{document}
\title{ENGR 40M Final Examination}
\date{INSERT DATE HERE}
\begin{center}
    \Large
    {\bfseries\makeatletter\@title\makeatother}
    \bigskip
    Stanford University
    \makeatletter\@date\makeatother
    \ifanswer
        \vspace{1pc}
        {\sffamily\bfseries SOLUTIONS}
        \vspace{1pc}
    \else
        \vfill
        \begin{tabular}{rp{10cm}}
            Name: & \hrulefill \\[1pc]
            SUNet ID: & \hrulefill @stanford.edu
        \end{tabular}
        \vfill
    \fi
    \normalsize
    \begin{tabular}{| >{\bfseries}c | c |}
        \hline
        Question & \bfseries Points \\
        \hline
        \hline
        % You need to fill this table in yourself, sadly.
         1 &  0 \\ \hline
         2 &  0 \\ \hline
         3 &  0 \\ \hline
         4 &  0 \\ \hline
         5 &  0 \\ \hline
         6 &  0 \\ \hline
        \hline
        Total & 0 \\
        \hline
    \end{tabular}
\end{center}
\ifanswer\else
    \vfill
    \textbf{Instructions:}
    \begin{enumerate}[label=\arabic*.]
        \item This examination contains \pageref{LastPage} pages, including this page.
        \item You have \textbf{three (3) hours} to complete the examination.  As a courtesy to your classmates, we ask that you not leave during the last fifteen minutes.
        \item Write your answers in this booklet.  We scan this into Gradescope, so \textbf{please try to avoid writing on the backs of pages}.  If you must do so, please indicate \textbf{very} clearly on the front of the page that you have written on the back of the page.
        \item You may use two (2) double-sided 8.5"\,$\times$\,11" pages with notes that you have prepared. You may not use any other resources, including lecture notes, books, other students or other engineers.
        \item You may use a calculator. You may not share a calculator with anyone.  If you didn’t bring a calculator, you may use your phone, \textbf{but} you must put it on \textbf{flight mode} and clear all visible notifications \textbf{before} the examination starts, and you must not open any applications other than the calculator and a timer.
        \item Please sign the below Honor Code statement.
    \end{enumerate}
    \fbox{\parbox{\textwidth}{
    In recognition of and in the spirit of the Stanford University Honor Code, I certify that I will neither give nor receive unpermitted aid on this examination.
    \vspace{1cm}
    \hspace*{\fill}
        Signature: \quad \rule{10cm}{0.5pt}
    \hspace*{\fill}
    \bigskip
    }}
    \clearpage
\fi
% Include questions from subfiles here:
\subfile{example}
\end{document}