Asset Depreciation Calculation


I have the following scenario where the Asset Depreciation is “Full month depreciation in month of purchase & no depreciation in month of sale”.

Asset Cost: Rs 15000
Asset Method: Straight Line Method
Asset life: 5 Years
Asset depreciation for the month: Rs 250
Asset Depreciation for the year: Rs 3000

However, on the system when I have applied the same scenario, the asset depreciation for the month is shown Rs 246.58.

I want to know how erpnext is calculating the depreciation.