Question

Find the number of 4-digit numbers that can be formed using the digits 1, 2, 4, 5, 6, 8 if digits cannot be repeated.

Answer 1

A 4 different digit number is to be made from the digits 1, 2, 4, 5, 6, 8 without repetition of digits.
∴ 4 different digits are to be arranged from 6 given digits which can be done in ⁶P₄
= `(6!)/((6-4)!)=(6xx5xx4xx3xx2!)/(2!)` = 360 ways
∴ 360 four-digit numbers can be formed if the repetition of digits is not allowed.