How does the Mahajani method of interest calculation work in BUSY? I need to use this but don't understand the formula.

In the Mahajani report, the first step is to define the party name and set the interest rate before opening the report. You can also choose whether you want to calculate interest monthly or annually. Let's now discuss the report column by column.
- Date: This column displays the date on which the voucher was entered.
- Type: This column displays the type of voucher, such as Payment or Receipt.
- Vch No.: This column displays the voucher number.
- Amount (Cr.): This column displays the amount credited in the voucher, or in simple words, the voucher amount.
- Days: The value in this column is calculated by subtracting the voucher date from the date on which interest is to be calculated (Ending-Date as entered in Report Options). For example, if you are calculating interest on 1st June and the voucher was entered on 1st May, then it will show 32 days in this column.
- Product (Cr.): The value in this column is calculated using the following formula: Amount (Cr.) / 30 * No of Days (as calculated in the above field). For example, if the amount credited is Rs. 60,000 and the number of days for which interest is to be calculated is 32, then this column will display the value as 64,000 i.e. 60,000/30 *32. Similar columns as explained above appear for amount debited i.e. Sale & Payment vouchers on the right-hand side.
- Balance Amount: This column displays the balance amount, i.e. total Amount (Cr.) - total Amount (Dr.).
- Balance Product: This column displays the balance product.
This column displays balance product i.e. total Product (Cr.) - total Product (Dr.).
Interest
This column displays the interest amount calculated by applying the following formula:
Balance Product * Rate of Interest/100 * 1/12 (divide by 12,only if you have specified interest rate annually)
For example, Balance Product is 1,41,334 and rate of interest is 12% per annum then interest will be 1413 i.e. 141334 * 12/100 *1/12.
Average Payment / Receipt Days
Average Payment / Receipt Days are calculated by applying the following formula:
Average Receipt = Net Interest / ( Total (Sale Current Year) *Interest Rate) / 360)
Average Payment = Net Interest / ( Total (Purchase Current Year) *Interest Rate) / 360)
For example, Net Interest = 1,413
 Total Sale Current Year = 1,00,000
 Interest Rate = 12%
 ∴ Average receipt days = 1,413 / ((1,00,000 *12%) / 360) = 42 Days