The total number of permutations of the letters of the word "$BANANA$" is

How many $3$-digit numbers can be formed by using the digits $1, 3, 6,$ and $8$,when the digits may be repeated any number of times?

In how many different ways can the letters of the word '$PRAISE$' be arranged?

There are $(n + 1)$ white and $(n + 1)$ black balls,each set numbered $1$ to $(n + 1)$. The number of ways in which the balls can be arranged in a row so that the adjacent balls are of different colours is

How many $2$-digit numbers are there with distinct digits?

The number of parallelograms that can be formed from a set of four parallel lines intersecting another set of three parallel lines is