答案1
有了排列数字,这一切就不那么困难了。
\documentclass[12pt]{article}
\PassOptionsToPackage{no-math}{fontspec}
\usepackage[sfdefault,lining,scaled=0.9]{FiraSans}
\usepackage{newtxsf}
\DeclareSymbolFont{digits}{TU}{\sfdefault}{m}{n}
\DeclareMathSymbol{0}{\mathalpha}{digits}{`0}
\DeclareMathSymbol{1}{\mathalpha}{digits}{`1}
\DeclareMathSymbol{2}{\mathalpha}{digits}{`2}
\DeclareMathSymbol{3}{\mathalpha}{digits}{`3}
\DeclareMathSymbol{4}{\mathalpha}{digits}{`4}
\DeclareMathSymbol{5}{\mathalpha}{digits}{`5}
\DeclareMathSymbol{6}{\mathalpha}{digits}{`6}
\DeclareMathSymbol{7}{\mathalpha}{digits}{`7}
\DeclareMathSymbol{8}{\mathalpha}{digits}{`8}
\DeclareMathSymbol{9}{\mathalpha}{digits}{`9}
\begin{document}
This is a test: $0123456789$ = 0123456789
$a-b=c$ abc
\end{document}