Find the unit digit of 3^45.

A1

B3

C7

D9

Explanation

Cyclicity of 3 is 4 (3^1=3, 3^2=9, 3^3=7, 3^4=1). Remainder of 45 / 4 is 1. So unit digit is 3^1 = 3.

Exam Relevance

Topic: Number System
Subtopic: Cyclicity

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