How many times should you expect to roll a 5 on a number cube if you roll the cube 4,000 times?

The probability of rolling a 5 on a number cube is 1/6, because there are a total of 6 numbers and you are picking just one, then, if you throw the cube 4000 times, the total amount of times you expect to get a 5 is:
(1/6)(4000) = 666