SOLUTION: A door lock has a 5 number keypad. How many different three digit codes are possible if the same number cannot be used twice in a row ?

Algebra.Com
Question 927030: A door lock has a 5 number keypad. How many different three digit codes are possible if the same number cannot be used twice in a row ?
Answer by Edwin McCravy(20055)   (Show Source): You can put this solution on YOUR website!
We choose the middle number first, any of 5 ways.
We choose the 1st number any of 4 ways.
We choose the 3rd digit also any of 4 ways.

That's 5*4*4 = 80 ways.

Edwin
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