Unformatted text preview: 1 5 . (b) Show that 2 has no multiplicative inverse mod 6. This means that 1 2 has no meaning when working mod 6. 8. Show that a natural number n is divisible by 3 iﬀ the sum of the digits is also divisible by 3. The Euclidean Algorithm 1. Find the gcd of each of the following pairs of numbers and write it as a sa + tb for some integers s,t . (a) 21,55 (b) 123, 323 2. Find the multiplicative inverse of 9 mod 20. 3. Solve the congruence 5 x ≡ 16( mod 21) 4. * Show that log 2 3 is irrational....
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 Summer '09
 RobBayer
 Math, Number Theory, Division, Greatest common divisor, Euclidean algorithm, Rob Bayer

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