Write the number of arrangements of the letters of the word BANANA in which two N’s come together.
Question:

Write the number of arrangements of the letters of the word BANANA in which two N’s come together.

Solution:

The word BANANA consists of 6 letters including three As and two Ns.

Considering both Ns together or as a single letter, we are left with 5 letters including three As.

$\therefore$ Number of arrangements of 5 things in which 3 are similar to one kind $=\frac{5 !}{3 !}=20$