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 distinct 5-digit numbers can be formed, using the digits 3, 4, 3, 4, 2?

How many three-digit numbers can be formed using the digits 2, 3, 4, 5, 6 if digits can be repeated?

How many distinct 5 digit numbers can be formed using the digits 3, 2, 3, 2, 4, 5.

How many 3-digit numbers can be formed from the digit 2, 4, 5, 6, 7 if no digit is repeated?

How many 10-digit numbers can be written by using the digits 1 and 2?

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?