Four letters E, K, S and V, one in each, were purchased from a plastic warehouse. How many ordered pairs of letters, to be used as initials, can be formed from them?
Given: the total number of letters = 4
To find: Number of ordered pairs of letters that can be formed like (E, K) or (S, E) etc.
Formula used:
Number of arrangements of n things taken r at a time = P(n, r)
∴ The total number of ways in which this can be done
= the number of arrangements of 4 things taken 2 at a time
= P(4, 2)
= 4 × 3
= 12
Hence, Number of ways in which ordered pairs of letters, to be used as initials, can be formed from given 4 letters are 12
17