How to write this formula in LaTeX?

Question

Does anyone how to write this formula in Latex?

Answer 1

It looks to me like a smallmatrix environment was used.

\documentclass{article}
\usepackage{amsmath} % for 'smallmatrix' env.
\begin{document}
$\mathcal{B} = (0.8 \begin{smallmatrix} +3.5 \ -2.3 \end{smallmatrix} ) \times 10^{-5}$
\end{document}