In how many different ways can the letters of the word KNOWLEDGE be arranged
in such a way that the vowels always come together?
We can choose the 3 vowels to be together (call it a "vowel trio") any of
these 3 ways: EEO, EOE, OEE.
For each of those 3 choices, there are 7 things (six single letters and one
vowel-trio). The 7 things are
K, N, W, L, D, G, (the vowel trio)
There are 7! ways to arrange those seven things:
Answer: 3∙7! = 3∙5040 = 15120 ways.
Edwin