Siddimaula

You can't use the change in accumulated depreciation because of asset sales and retirement of fully depreciated assets.

For CFA purposes you will be given the numbers pretty clearly so don't worry about. For the real world you'll have differences related to depreciation expense being captured in other lines on the income statement and balance sheet as was previously mentioned. Use the number in the cash flow statement. It's the most accurate measure of the decline in valuem of net PPE attributable to passage of time and/or consumption of an asset.