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Printjmc
number theory senior
Problem
Compute the multiplicative inverse of modulo . Express your answer as an integer from to .
Solution
Let be the inverse of modulo . Then, by the definition of the inverse, . We are looking for an integer that satisfies this congruence.
To make our task easier, we note that , and so Now we write as : Thus, the inverse we seek is .
To make our task easier, we note that , and so Now we write as : Thus, the inverse we seek is .
Final answer
180