Probability of a roll of the dice

The following question came up on a practice exam and I am having trouble understanding the formulation to solve the problem.

A) Calculate the possibility of throwing six 6’s in six throws with an unbiased

die.

B) Calculate the possibility of throwing a 6 exactly once in six throws with

an unbiased die.

For A), I have considered that each roll of the dice is always 1/6. Therefore is it correct to assume that the formula would be (1/6).(1/6).(1/6).(1/6).(1/6).(1/6). Is this correct? And I am lost when it comes to B).

Thank you...

Matty