Standard form in TeX?

Question

How do I write x10 to the power of something within an equation?

At the moment I'm using y \times 10^x, but it gets slightly confusing if I have a long line of numbers that I'm multiplying together.

This the equation I have now:

g = \frac{6.67 \times 10^{-11} \times 6 \times 10^{24}}{6400010^2}

Which produces the output:

Answer 1

If you need to typeset actual numbers (and not symbols as in your example), you could use the \num macro provided by siunitx. It allows you to type \num{2e3} to output , both in math and in text mode.

When multiplying numbers in exponential form, you could reduce the spacing within the numbers, using tight-spacing=true:

\documentclass{article}
\usepackage{siunitx}

\begin{document}

\sisetup{tight-spacing=true}
\[
g = \frac{\num{6.67e-11} \times \num{6e24}}{6400010^2}
\]
\end{document}

Answer 2

I know many will disagree with the following but nonetheless this what I used to use:

\newcommand{\sn}[2]{\ensuremath{{#1}\times 10^{#2}}}

And I use it like this: \sn{y}{x}. Here is an example:

\documentclass{article}
\usepackage[dvipsnames]{xcolor}
\usepackage{amsmath}

\newcommand{\sn}[2]{\ensuremath{{#1}\times 10^{#2}}}

\begin{document}
\begin{align*}
(\sn{2.25}{\textcolor{Cerulean}{4}})(\sn{7.5}{\textcolor{OrangeRed}{6}})    &= \sn{(2.25)(7.5)}{\textcolor{Cerulean}{4}+\textcolor{OrangeRed}{6}}\\
                               &= \sn{16.875}{10}\\
                               &= \sn{1.6875}{11}\\
                               &= \sn{1.7}{11} \quad(\text{2 s.f.})
\end{align*}
\end{document}