Given: We have 6 letters
To Find: Number of ways to arrange letters P,E,N,C,I,L
Condition: N is always next to E
Here we need EN together in all arrangements.
So, we will consider EN as a single letter.
Now, we have 5 letters, i.e. P,C,I,L and ‘EN’.
5 letters can be arranged in 5P5 ways
⇒ 5P5
⇒ \(\frac{5!}{(5-5)!}\)
⇒ \(\frac{5!}{0!}\)
⇒ 120
In 120 ways we can arrange the letters of the word ‘PENCIL’ so that N is always next to E.