How many 4-letter words with at least one consonant can be constructed from the letters A, B, C, D, E, and F? (Note that B, C, D, and F are consonants, any word is valid, not just English language words, and letters may be used more than once.)
A, B, C, D, E, F ==6 Letters.
For the first place , you have 6 choices.
For the 2nd place, you still have 6 choices [because you are allowed to repeat them]
For the 3rd place, you still have 6 choices, for the same reason as above.
For the 4th place, you have 4 choices [because you only have 4 consonants]
So, I think the total number of 4-digit permutations== 6 x 6 x 6 x 4==864 permutations possible.
