SOLUTION: 1. How many different 4-digit numbers can be formed from the digits 2, 3, 4, 5, 6, 7, and 9: a) if repetition of digits is NOT allowed? b) if repetition of digits is allowed?

Question 1194442: 1. How many different 4-digit numbers can be formed from the digits 2, 3, 4, 5, 6, 7, and 9:
a) if repetition of digits is NOT allowed?
b) if repetition of digits is allowed?
c) How many of them are odd numbers?
d) How many of them are even numbers?

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
1. How many different 4-digit numbers can be formed from the digits 2, 3, 4, 5, 6, 7, and 9:
a) if repetition of digits is NOT allowed?
There are 7 numbers.
The 1st choice is 1 of 7, then 1 of 6, 1 of 5, 1 of 4.
---> 7*6*5*4
==================
b) if repetition of digits is allowed?
Each selection is 1 of 7 ---> 7*7*7*7
=============================
c) How many of them are odd numbers?
With or without repetition?
d) How many of them are even numbers?
With or without repetition?

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