There are times that I would want to list the File permissions in the current working directory. To do this, I would use the ls -l command which lists the files and shows the Textual representation of file permissions. But for some reason I would want the Numeric representation such as 777, 755, etc. In order to achieve this, you can simply do stat -c "%a %n" *. If you often use this you may want to add in your .bashrc this line:

alias statls='stat -c "%a %n"'

Then reload your .bashrc by doing . ~/.bashrc. You can use the alias like so statls * or statls dir/*.

For changing permissions, you can do chmod u+x file and such. But if you want to also use Numeric format, you can simply remember this format (the data on the table). Or, you can just remember rwx to be similar to 421 e.g. you want it to be r-- so it's 4 or r-x so it's 5. If you want the permission of the file foo to come out as something like rwxr-xr-x, you can do chmod 755 foo.

Cheers. :D