Please help!! I don’t know how to solve this. Which one is the digit of the units in 3^81:

Mathematics

1 answer:

egoroff_w [7]2 years ago

3 0

Solution:

3⁸¹ = 3⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹ ⁺ ⁹
3⁸¹ = 3⁹ x 3⁹ x 3⁹ x 3⁹ x 3⁹ x 3⁹ x 3⁹ x 3⁹ x 3⁹
3⁹ = 19683 [Using Calculator]

This means that the Unit digit of 19683 is 3. For each number, multiply the unit's digit of 3⁹.

3 x 3 x 3 x 3 x 3 x 3 x 3 x 3 x 3
=> 19683
=> Unit digit of 3⁸¹ = 3

Option A is correct.

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