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\begin{document}
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\begin{table}[!h]
  \centering
  \begin{subtable}{0.48\textwidth}
    \centering
    \label{stock1}
    \begin{tabular}{|c|c|>{$}c<{$}|}
    \hline
    M & Million &10^6\\\hline
    B & Billion &10^9\\\hline
    T & Trillion &10^{12}\\\hline
    Q & Quadrillion &10^{15}\\\hline
    QQ & Quintillion &10^{18}\\\hline
    S & Sextillion &10^{21}\\\hline
    SS & Septillion &10^{24}\\\hline
    O & Octillion &10^{27}\\\hline
    N & Nonillion &10^{30}\\\hline
    D & Decillion &10^{33}\\\hline
    UD & Undecillion &10^{36}\\\hline
    TD & Duodecillion &10^{39}\\\hline
    QD & Tredecillion &10^{42}\\\hline
    Qn & Quattuordecillion &10^{45}\\\hline
    SX & Quindecillion &10^{48}\\\hline
    SP & Sexdecillion &10^{51}\\\hline
    \end{tabular}
    \caption{Values up to Sextillion}
  \end{subtable}
  \hfill
  \begin{subtable}{0.48\textwidth}
    \centering
    \label{stock2}
    \begin{tabular}{|c|c|>{$}c<{$}|}
    \hline
    OC & Septendecillion &10^{54}\\\hline
    NO & Octodecillion &10^{57}\\\hline
    CE & Novemdecillion &10^{60}\\\hline
    DE & Vigintillion &10^{63}\\\hline
    VI & Unvigintillion &10^{66}\\\hline
    WI & Duovigintillion &10^{69}\\\hline
    W2 & Trevigintillion &10^{72}\\\hline
    W3 & Quattuorvigintillion &10^{75}\\\hline
    W4 & Quinvigintillion &10^{78}\\\hline
    W5 & Sexvigintillion &10^{81}\\\hline
    W6 & Septenvigintillion &10^{84}\\\hline
    W7 & Octovigintillion &10^{87}\\\hline
    W8 & Novemvigintillion &10^{90}\\\hline
    W9 & Trigintillion &10^{93}\\\hline
    WW & Untrigintillion &10^{96}\\\hline
    \end{tabular}
    \caption{Values from Septendecillion to Untrigintillion}
  \end{subtable}
  \caption{Numeric Values in Scientific Notation}
\end{table}

\end{document}