For each day:
# yesterday's balance + (yesterday's balance * interest)
# example:
balance = 1.234
interest = 0.023
new balance = (1.234 +( 1.234 * 0.023)) = 1.262382
if there are new deposits add into new balance here.
Next day
I have done simmilar calculations and figured out that you have from the earnings probably also to withdraw 10% as some kind of management/success participation fee/ or name it like you want
But this is only my opinion/idea of how to calculate the numbers
No, they simply truncate from 5 to 8 decimal position digits giving you the result of the percentage calculation with only 4 decimal digits
Example
Capital at a day : 1.17
Percent of the day : 1.5%
Interest calculates : 1.17 * 1.5 / 100 = 0.01755
Interest rounded : 0.0175
New capital at the end of the day : (1.17+0.0175) 1.185 (This is the new capital of the day to calculate new percentage the next day)
Hope to be clear....
Cheers