need a regular expression hint

I am putting the finishing touches on the new formatter,

    > but I need to figure out how to do a regular expression
    > that will match each of these strings:

    > r'$10$' r'$+7.3567{\times}10$' r'$-5.740977777{\times}10$'
    > r'${\times}10$'

Rather than trying to craft the mother of all regexes, you may want o
make a series of them. Iterate over the series and if one matches,
use it.