What is the unit digit in product (3 pow 65 * 6 pow 59 * 7 pow 71)

We know that we

3 pow 4 gives us 51
7 pow 4 gives us 2401
We will always get a 6 as unit digit for every power of 6

Now lets rewrite our expression

(3 pow 4) pow 16 *3 *6 * (7 pow 4) pow 17 *7 pow 3

Which is
1*3*6*1*7 pow 3

Unit digit of 7 pow 3 =3

1*3*6*1*3=54

Hence unit digit is 54