since it appears it is a pyramid I did some figuring with a sky between each level of 10 mi it would take 7 levels to house over 3.6 Billion using a average of 2 5/8 acre for each person(some will have more and some will have less I am using 5 acres(466' 8.28125" x 466' 8.28125") as the top and .25 acre(104' 4.25" x 104' 4.25") as the smallest) . each level would be as follows:
 
1) 1500x1500
2) 1490x1490
3) 1480x1480
4) 1470x1470
5) 1460x1460
6) 1450x1450
7) 1440x1440
 
using a sky of 20 mi it would still take 7 levels for over 3.5 B using the same housing estimate they would be:
 
1) 1500x1500
2) 1480x1480
3) 1460x1460
4) 1440x1440
5) 1420x1420
6) 1400x1400
7) 1380x1380
 
 
since nearly 1.7-1.75 billion kids are under the age of accountability they will ALL be raptured and between the number of belivers ratured killed in the tribulation and who have died since the begining I thing about 1.75-1.9 billion is a good estimate.  propably a bit on the high side.
 
what are your thoughts???
 
Paul