Beginner doubt on closing stock of purchased goods

Hi friends,

I am trying to understand Closing Stock as beginner to Journal entries

This is the scenario for finding Closing entry for sales and closing stock

June 30 2017,  Purchased 10 Mobile Sets for Rs.1,000,00

July 30 2017,   Rs.500 added to each of 5 Mobile Sets Sales made so far = Rs.52500

Jul 30 2017,  One  demo piece worth purchase Rupees Rs.10000

Jul 30 2017, Stock remaining of purchase value for remaining 4 mobile set Rs.40000

Jul 30 2017, Depreciatio @ 25% of existing stock less Rs.40000 is Rs.10000

Jul 30 2017, Closing Stock is Rs. Rs.30000

Is above depreciation considered for calculating Closing Stock value?

Is less demo piece value correct way?

Is this correct to calculate closing stock value.

Please guide.