Find the number of 5-digit telephone numbers having at least one of their digits repeated.

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

Find the total number of 9-digit numbers which have all different digit

Find the number of 6-digit numbers using the digits 3,4,5,6,7,8 without repetition. How many of these numbers are (a) divisible by 5 (b) not divisible by 5

How many six-digit telephone nunmbers can be formed if the first two digits are 45 and no digit can appear more than once?

How many three digit numbers are there, with no digit repeated?

How many 5 digit telephone numbers can be constructed using the digits 0 to 9, if each number starts with 67 and no digit appears more than once?