Solutions

1.	755 is rwxrwxr-x
	744 is rwxr--r--
	770 is rwxrwx---
	764 is rwxrw-r--
	666 is rw-rw-rw-
	644 is rw-r--r--

2.	chmod 000 memo

	The rm command won't let you remove the file without confirmation,
	even though you own it, because you have removed write permission,
	even for yourself.

3.	Work in pairs.  Note that you can remove your partner's no-
	permissions file if the directory that it sits in allows you
	write permission.

4.	$ chmod go+wx temp

 	This will add write and execute permissions to group and other.


	$ chmod o-x,u+x temp

 	This will subtract execute permission from other, and add execute 
	permissions to the owner.
