David Carlisle <d.p.carlisle at gmail.com> writes: > \input picture > \catcode`\@=11 > > \RequirePackage{cancel} > \let\zzcancel\cancel > \def\cancel#1{{% > \let\line\LaTeX at line > \zzcancel{#1}}} > > $\cancel{x^2 + 1}$ > > $\cancel{a}$ > > $\cancel{{x^2 + 1 \over b}}$ > > > \bye Fantastic...!!