How is late charges calculated when using simple interest calc method

Dear guru's,

Your assistance and guidance is required.

Customers are setup for interest calculation method of 'simple'. Now as far as I have read up this is then calculated as follows. This is based per transaction as each transaction could have different # of Days Overdue:

Amount Overdue * (Rate / 100) * (# of Days Overdue / # of Days in Period)

25864,30 * (10,25/100) * (1071/30)

So test case as follows:

Overdue Amount	Days Late	Interest	Rate	Charge
25 864,30	1071	30	10,25	217,9

I dont understand how system came to 217,90 using above simple method?

What am I missing … running those numbers through the formula does not bring back 217,90….

Please advise

Thanks

Chez