070403 formula for adding x periods/mo add 11% to each

hi, trying to find progress on a number: 100 starting apr 1, add 11% each 4
business days.
trying to get a separate progress for each month.

have figured business days as: (Jan-Dec)
22 20 22 21 23 22 23 22 21 22 21 22

days /mo: 21.75 days /yr: 261 reps /yr: 65.25 reps /mo:
5.4375

guessing start 1st col with months, next with start figure in apr: 100
column: monthly totals (times 5.4375 reps..)
column: running total

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don't know if this is similar to old math trick start with add 1 penny on
1st day of month, double that every day for 30 days equals...