How many 4-letter words with or without meaning, can be formed out of the letters of the word, LOGARITHMS, if repetition of letters is not allowed?
40
400
5040
2520
Explanation:
LOGARITHMS contains 10 different letters.
Required number of words= Number of arrangements of 10 letters, taking 4 at a time.
= 10P4=$\left (10 \times 9 \times 8 \times 7\right)$= 5040.