$2$:$47$

$2$

Section

Name:

$($a$)(2$ points$)$ Consider the following zip code:

$20500-0001$

What is the check digit?

$($b$)(2$ points$)$ Determine the digit $x$ that makes the number $8457938345$ divisible by $9.$

$($c$)(6$ points$)$ For the following ISBN$-10,$ determine the check digit:

$1-4642-2948-?$