Question 1175610
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Coloso University uses a 5-digit {{{highlight(cross(restriction))}}} ZIP-code to distribute mails and packages. 
How many ZIP codes are there if there are no digit restrictions? How many ZIP codes are possible if repetition is not allowed?
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<pre>
{{{10^5}}} = 100,000  codes, if repetition is allowed.

                 Because you have 10 opportunities for digits in EACH POSITION, independently.



10*9*8*7*6 =  30,240  codes, if repetition is not allowed.
</pre>

Solved.



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