D. This problem concerns numbers written in base 9. The base 10 number 115 is expressed in base 9 as the number 1379 since 1379 = (a) For a number n base 9, find a test for determining if n is a...

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Extracted text: D. This problem concerns numbers written in base 9. The base 10 number 115 is expressed in base 9 as the number 1379 since 1379 = (a) For a number n base 9, find a test for determining if n is a multiple of 5 using the digits of n when written as a base 9 number. Show that you test works for n = 115 = 1379. (b) Prove your answer from (a) 1. 92 +3.9 +7=115