Type the number of the spelling rule that applies to the word.

beautiful

4

Explanation:

If the suffix begins with a consonant and the main word ends with letter y following a consonant, change the y to i.

(happy + ness = happiness) Exception: If the word is a verb adding - ing, do not change the y.

The answer is changing the vowel Y to an I.

Explanation:

There is a general rule which says that if the word ends with a vowel Y preceded by a consonant, it changes to an I when added a suffix. So if we take the root of the word beautiful which is beauty, we see that it ends with a vowel y with the consonant t before it, so when adding a suffix - ful the vowel changes. E. g. lady - ladies, pity - pitiful. However, you should bear in mind that this rule just like any other has exceptions.