Hmmm... I don't mean to keep poking at a not-too-serious answer, but I don't think that works exactly right either. What happens with numbers like 'seven' or 'ten' that have an 'e' in the middle, but not at the end? The last non-matching-non-'e' part gets removed.

Update: for that matter, the numbers w/o an 'e' in them at all are being nulled out...
Update2: Updated code now seems to work properly, $str is built up while $_ is torn down...

-Blake