Question

Find the number of $4$ letter words, with or without meaning, which can be formed out of the letters of the word $\text{ROSE,}$ where the repetition of the letters is not allowed.

Answer 1

Step 1:
Finding number of ways.
Number of ways to fill the first place $=4$
Number of ways to fill the second place $=3$
Number of ways to fill the third place $=2$
Number of ways to fill the fourth place $=1$

Step 2:
Using multiplication principle.
$\therefore$ Number of four letter words $=4\times 3\times 2\times 1=24$
Hence, required total number of words are $24$.