What method can you call to determine the current time in milliseconds? What does it mean to say…

What method can you call to determine the current time in
milliseconds? What does it mean to say that an algorithm is quadratic? When you
apply the radix sort algorithm, do you perform the first sorting pass on the
most significant digit or the least significant digit? Why? What is the
closed-form expression that computes the sum of the series

N + N1 + N2 + . . . + 3 + 2 + 1