Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 5 - Number Theory and the Real Number System - 5.1 Number Theory: Prime and Composite Numbers - Exercise Set 5.1 - Page 256: 71


d = 6

Work Step by Step

Consider 8|76,523,45d when d is equal to 6. For a number to be divisible by 8, its last three digits must make a number divisible by 8. In our case, the last digit (the ones digit) is unknown. The three digit number we use looks like this: 45d, with d being an unknown value. If we substitute each number 0 through 9 for d and then check to see if the number is divisible by 8, we find that only 456 is divisible by 8.
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