List and execute UNIX command to display the sizes of the six largest files in the current directory listed in ascending order of their size?

There are several ways to do this (typical Unix ...).

you could execute the following command:

du | sort -n | tail -6

The 'du' command lists disk usage by listing a file name and size per line, then use the sort command to list numerically, and the last 6 will be the 6 largest.