In how many ways can the letters of the word “PROBLEM” be rearranged to make 7 letter words such that
none of the letters repeat?

A. 7

B. 7C7
C. 77
D. 49
E. None of these


The answer is 7P7 = 7!. There may be a typo in option A.

There are 7 letters and none is common, so 'n' objects taken all at a time can be arranged (Permutation) in 7P7 ways = 7!.