Skip numbering.
Skip-1000:
When 1000 notes are printed in one "stack" before the next consecutive serial number appearsat the bottom of the next "stack"
Example:
Position A1:
1240000- 1240999 all with FP/BP: 55/76
Position A2:
1241000- 1241999 all with position numbers 58/78.
They are in groupings of 1000.
Now, we now know that BABN sheets are 40notes per sheet. The notation for that is "40/on". That means that there are 40 groups (stacks) of 1000 notes. The serial numbers will make a "consecutive run" from the first note of A1 to the last note of H5.
Or, 40 stacks of 1000 notes high, = 40,000 notes. That is a ream. The ream size is 40,000 notes.
As you can see, it is dependant on the skip-numbering.
If it were skip-500, then ream size would be 20,000.
If it were skip 6000, on a sheet of 45 (such as the CBN $20 replacements), then the ream size is: 6000 (notes high) x 45 stacks (of 6000) = 270,000 notes.
If it were skip 8000, on a sheet of 45 (such as the CBN EZL 8.64 $20 replacements), then the ream size is: 8000 (notes high) x 45 stacks (of 8000) = 360,000 notes.
Hope this helps.