Memory part 3: Virtual Memory

"On x86-64 with 4kB pages and 512 entries per directory this allows the addressing of 2MB with a total of 4 directories (one for each level). 1GB of contiguous memory can be addressed with one directory for levels 2 to 4 and 512 directories for level 1. "

==> addressing 1 page with a total of 4 directories (one for each level), 2MB of contiguous memory can be addressed with one directory for levels 2 to 4 and 512 directories for level 1.

is it correct ?