Drop the e when adding a suffix beginning with a vowel.
examples:
barbecue -> barbecuing
adventure -> adventurous
appreciate -> appreciative
Don't drop the e when adding a suffix beginning with a consonant.
examples:
gentle -> gentleness
grace -> graceful
Exception - when the word ends in ge or ce and the suffix begins with a or o don't drop the e
examples : notice -> noticeable
courage -> courageous