Unprint a line on the console in Python?

What you're looking for is:

print("{}/100".format(k), "\r", end="")

\r is carriage return, which returns the cursor to the beginning of the line. In effect, whatever is printed will overwrite the previous printed text. end="" is to prevent \n after printing (to stay on the same line).

A simpler form as suggested by sonrad10 in the comments:

print("{}/100".format(k), end="\r")

Here, we're simply replacing the end character with \r instead of \n.

In Python 2, the same can be achieved with:

print "{}/100".format(k), "\r",