8 x 8 x 8...=


8 is a 1st Level 8-PAC,
8 X 8 = 64, this is a complete 2nd Level
8 X 64 = 512 is a complete 3rd Level.
8 X 512 = 4,096 makes a complete 4th Level etc.
8 X 4,096 = 32,768 makes a complete 5th Level
8 X 32,768 = 262,144 makes a complete 6th Level
8 X 262,144 = 2,097,152 makes a complete 7th Level
8 X 2,097,152 = 16,777,216 makes a complete 8th Level
8 X 16,777,216 = 134,217,728 makes a complete 9th Level
8 X 134,217,728 = 1,073,741,904 makes a complete 10th Level
8 X 1,073,741,904 = 8,589,935,232 makes a complete 11th Level

You just keep multiplying by 8 to reach the next complete Level.

There are now about 7 billion people on the Earth, so an incomplete 11th Level would handle everybody.