Linux Permissions simplified for me

r = Read permissions = 4
w = Write permissions = 2
x = Excute permissions = 1

Total = 7

3 parts to permissions:

Part 1 = User
Part 2 = Group
Part 3 = World

So "rw-r--r--" = 644
and "rwx-r--r--" = 744
and "rwxrwxrwx" = 777
and "rwxr-xr-x" = 755