How many ways can the letters of the word BANANA be arranged so that “All the A’s come together”

Given word BANANA

Given word contains 6 letters in which 3A’s are alike 2N’s are alike and one B.

Treat the 3A’s as one unit. Then we have $3+1=4$ entities in which 2N’s are alike and rest are different.

They can be arranged in $\frac{4!}{2!}$ ways.

The 3A’s among themselves can be arranged in $\frac{3!}{3!}=1$ way

$\therefore$ The number of required arrangements $=\frac{4!}{2!}\times 1$

$=12$