Please compare these 2 sentences.
1, lf you are overqualified for a particular job, you have more experience or training than __ is needed. (Longman Dictionary of Contemporary English)
2, The magnification is usually at least thirty times greater than what is normally seen with the naked eye. (Longman Dictionary of Contemporary English)
In the first sentence, there is a blank after "than", while, in a similar case, sentence 2, a "what" is put in that blank.
I want to make sure if, in both of the the sentences above, a what is optional.