Question

46. How many different four-letter codes are there if only the letters A, B, C, D, E, and F can be used and no letter can be used more than once?

Answer 1

Solution

total alphabets are 6 in number

it means on the first position there can be any alphabet from the 6 alphabet

Now, we can't repeat the letters therefore, remaining choices are from 5 alphabets so, in second position any alphabet from the remaining 5 can be placed

now remaining alphabets are 4 so, third position can be taken by any of the 4 alphabets

now for the fourth position there are only 3 alphabets from which we can place the alphabets

so, total four alphabetical letters with the given alphabets are 6×5×4×3=360

so, there can be 360 four letters code can be made.