How many four digit odd numbers can be created using the digist 1 through 7?


2 Answers

Chris Kimmel Profile
Chris Kimmel answered
Okay. We have 1, 2, 3, 4, 5, 6, and 7. These are our 7 digits we can work with.

Our four-digit number will be this: Abcd
a, b, c, and d are digits.

A has 7 possible values,
b has 7 possible values,
c has 7 possible values, and
d has 4 possible values (1, 3, 5, and 7, since all numbers ending in any of these digits is odd.)

So, 7*7*7*4=

1372 possible odd four digit numbers.
Oddman Profile
Oddman answered
If digits cannot be repeated, the least significant digit can be one of four values,{1, 3, 5, 7}. The next most significant digit can be one of the 6 remaining values. The second most significant digit can be one of the 5 remaining values, and the most significant digit can be one of the 4 remaining values.

The number of 4-digit odd numbers with no digits repeated is 4*6*5*4 = 480.
thanked the writer.
Chris Kimmel
Chris Kimmel commented
Interesting. I never thought of it that way. Thanks! I wouldn't have been able to come up with that.

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