How do I expand this number into full decimal (non-scientific) notation?

Question

I need to typeset the result of 88.6 to the 53rd power multiplied by 9216.

What I need is the full number, as part of a 6 page long equation of how long it would take to walk to the Andromeda Galaxy at 4 Mph. It should not be in scientific notation.

Answer 1

Unfortunately, bigintcalc allows computations only with integers. But in this case you know the number of digits in the integer part: the base 10 logarithm of 88.6^53 * 9216 is, approximately 107.178 and so we can perform the operation in integer arithmetic and adjust the result to have 108 digits in the integer part:

\documentclass{article}
\usepackage{xparse,l3str,bigintcalc}
\usepackage{numprint}

\npthousandsep{\hspace{.33333em plus .16667em minus .11111em}}
\npdecimalsign{.}

\ExplSyntaxOn
\NewDocumentCommand{\xnumprint}{mm}
 { % #1 = bigint expression, #2 = decimal places
  \tl_set:Nx \l_tmpa_tl { #1 }
  \tl_set:Nx \l_tmpb_tl { \str_substr:Nnn \l_tmpa_tl { #2 } { } }
  \tl_set:Nx \l_tmpa_tl { \str_substr:Nnn \l_tmpa_tl { } { #2 } }
  \use:x { \exp_not:N \numprint { \l_tmpa_tl.\l_tmpb_tl } }
 }
\ExplSyntaxOff
\begin{document}

\noindent\xnumprint{\bigintcalcMul{\bigintcalcPow{886}{53}}{9216}}{108}

\end{document}

Answer 2

Here is how:

\documentclass{article}
\usepackage{bigintcalc}
\begin{document}
\bigintcalcMul{\bigintcalcPow{86}{53}}{9216}
\end{document}

To format it:

\documentclass{article}
\usepackage{numprint}
\npthousandsep{ }
\usepackage{bigintcalc}
\begin{document}
\numprint{\bigintcalcMul{\bigintcalcPow{86}{53}}{9216}}
\end{document}

(Just a small error on the decimal).

You may also find this How to typeset large numbers, useful.

You might also like to place it in a parbox and add a phantom character to line up the thousands,