Question 634815
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Hi,
How many different 4-digit numbers can be formed from the {{{6}}} digits 2, 3,4,5,6,7, and 8 if: 
a. Repetition of digits is not allowed?  {{{6*5*4*3}}}
b. Repetition of digits is allowed? {{{6*6*6*6}}}
c.How many of them are odd numbers? Refer to letter a.{{{6*5*4*3/2}}}
d. How many of them are even numbers?Refer to letter b.{{{6*6*6*6/2}}}