Dep Calculation issue

Hello Experts,

I have a case

We are using Daily basis Depreciation Calculation.

DIPS = 01-Jul-2015

Cost   120,000

Life 2 Year.

and i did unchecked Depreciation flag in Aug period and Enable to Sep Period with Amortization adjustment and also increase One Month, it means now showing 2 year and 1 Month

Jul Depreciation =5,095.89

Aug Depreciation Zero

and Sep = 4,935.62.

I am confused that how system has calculate Sep Period Depreciation which formula has used in system.

Thanks