What is the unit digit of 3987654 Explain how we can answer

What is the unit digit of 3^987654? Explain how we can answer this question without actually computing 3^987654.

5 (10 points). What is the unit digit of 3087654? Explain how we can answer this question without actually computing 3987654

Answer to the question is as follows:

3^987654 \'s last digit will be ?

3 has a cyclicity of 4, meaning every 5th number will have the same end number as 1st

3^1 = 3 <-- last digit 3

3^2 = 9

3^3 = 27

3^4 = 81

3^5 = 243 <-- last digit 3

3^987654 can be expressed as 3^(987652+2) = 3^(4k+2) whose last digit will be 3^2 ( because 3 has cyclcity of 4 for the same ending digit)

Hence, the last digit is 9