Question

find the unit digit of 9 power 85​

Answer 1

Answer:

The unit digit of $9^{85}$ is 9.        

Step-by-step explanation:

Given : Expression $9^{85}$

To find : The unit digit of the expression?

Solution :  

First we determine the cyclicity of number 9.

$9^1=9$

$9^2=81$

$9^3=729$

$9^4=6561$

The cyclicity of 9 is 2.

Now with the cyclicity number i.e. with 2 divide the given power

i.e. 85 ÷ 2

The remainder will be 1.

The required answer is 9 raised to the power 1 is 9.

Therefore, The unit digit of $9^{85}$ is 9.