SILENT 'E' RULE

This is sometimes called magic or lazy e.
Drop the final e before a vowel suffix: like liking.
BUT keep it before a consonant suffix: like likely

ing is a vowel suffix because it begins with a vowel and ly is a consonant suffix because it starts with a consonant.

The reason is that the vowel in the new ending will keep the first vowel long just as the e did. Drop the e when you do not need it.  N.B. manageable where the e keeps the g soft.
Exceptions: vicious, artificial, racial etc.  The i here does not lengthen the first vowel because it forms a sh sound which alerts you to the exception.