If you need math sym­bols in­fre­quently—some light ad­di­tion and sub­trac­tion, the oc­ca­sional neg­a­tive num­ber—you can get by with­out spe­cial sym­bols. Use the plus sign (+) and equals sign (=) as usual. Use the en dash as a mi­nus sign (–) (see hy­phens and dashes).

If you need to do mul­ti­pli­ca­tion or be­yond, in­sert real math sym­bols by hand.