The exercises appear to involve basic mathematical operations. It is vital to identify the operations needed, calculate each exercise step-by-step, and check your work for accuracy. Practicing similar problems will also help you understand better.
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The answers to the modular arithmetic problems are: 4 mod 3 = 1 , 5 mod 2 = 1 , 11 mod 5 = 1 , and 13 mod 4 = 1 . ;