The probability that the sum of the numbers rolled is either even or a multiple of 5 is 11/18.
The probability of rolling a multiple of five on a standard die is 1 in 6, or about 0.1667.The probability of rolling a 10, 15, or higher is zero, because the question implied only one die.
i dont know what they are called but they are easy to find. just go to youir local auto store. they will show you. It is called a Torx.