please calculate inventory turnover and give a detailed explanation

Amazon Financial Statement Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions Dec. 31, 2018 $ 232,887 4 Total net sales 5 Operating expenses: 6 Cost of sales 7 Fulfillment 8 Technology and content Marketing 139,156 34,027 28,837 13,814 4,336 296 220,466 12,421 440 (1,417) (183) (1,160) 11,261 (1,197) 9 10 General and administrative 11 Other operating expense (income), net 12 Total operating expenses 13 Operating income 14 Interest income 15 Interest expense 16 Other income (expense), net 17 Total non-operating income (expense) 18 Income before income taxes 19 Provision for income taxes 20 Equity-method investment activity, net of tax 21 Net income 22 Basic earnings per share 23 Diluted earnings per share 24 Weighted-average shares used in computation of earnings per share: 25 Basic (in shares) 26 Diluted (in shares) 27 Net product sales 28 Total net sales 29 Net service sales 30 Total net sales $ 10,073 $ 20.68 $ 20.14 487 500 $ 141,915 $ 90,972 Dec. 31, 2018 Consolidated Balance Sheets - USD ($) $ in Millions Current assets: Cash and cash equivalents Marketable securities Inventories Accounts receivable, net and other Total current assets Property and equipment, net $ 31,750 9,500 17,174 16,677 75,101 61,797 14,548 11,202 162,648 Operating leases Goodwill Other assets Total assets Current liabilities: Accounts payable Accrued expenses and other Unearned revenue Total current liabilities Long-term lease liabilities Long-term debt Other long-term liabilities Commitments and contingencies (Note 7) Stockholders' equity: Preferred stock, $0.01 par value: Authorized shares - 500 Issued and outstanding shares Common stock, $0.01 par value: Authorized shares - 5,000 Issued shares - 507 and 514 Treasury stock, at cost Additional paid-in capital Accumulated other comprehensive income (loss) Retained earnings Total stockholders' equity Total liabilities and stockholders' equity Ratins Ratio formulas 38,192 23,663 6,536 68,391 9,650 23,495 17,563 (1,837) 26,791 (1,035) 19,625 43,549 $ 162,648 Consolidated Statements of Cash Flows - USD ($) $ in Millions Dec. 31, 2018 $ 21,856 10,073 15,341 5,418 274 219 441 (1,314) (4,615) 3,263 Statement of Cash Flows [Abstract] CASH, CASH EQUIVALENTS, AND RESTRICTED CASH, BEGINNING OF PERIOD OPERATING ACTIVITIES: Net income Adjustments to reconcile net income to net cash from operating activities: Depreciation and amortization of property and equipment and capitalized content costs, operating lease assets, and other Stock-based compensation Other operating expense (income), net Other expense (income), net Deferred income taxes Changes in operating assets and liabilities: Inventories Accounts receivable, net and other Accounts payable Accrued expenses and other Unearned revenue Net cash provided by (used in) operating activities INVESTING ACTIVITIES: Purchases of property and equipment Proceeds from property and equipment sales and incentives Acquisitions, net of cash acquired, and other Sales and maturities of marketable securities Purchases of marketable securities Net cash provided by (used in) investing activities FINANCING ACTIVITIES: Proceeds from long-term debt and other Repayments of long-term debt and other Principal repayments of finance leases 472 1,151 30,723 (13,427) 2,104 (2,186) 8,240 (7,100) (12,369) 768 (668) (7,449) (13,427) 2,104 (2,186) 8,240 (7,100) (12,369) Purchases of property and equipment Proceeds from property and equipment sales and incentives Acquisitions, net of cash acquired, and other Sales and maturities of marketable securities Purchases of marketable securities Net cash provided by (used in) investing activities FINANCING ACTIVITIES: Proceeds from long-term debt and other Repayments of long-term debt and other Principal repayments of finance leases Principal repayments of financing obligations Net cash provided by (used in) financing activities Foreign currency effect on cash, cash equivalents, and restricted cash Net increase (decrease) in cash, cash equivalents, and restricted cash CASH, CASH EQUIVALENTS, AND RESTRICTED CASH, END OF PERIOD SUPPLEMENTAL CASH FLOW INFORMATION: Cash paid for interest on long-term debt Cash paid for operating leases Cash paid for interest on capital leases Cash paid for interest on finance leases Cash paid for interest on financing obligations Cash paid for income taxes, net of refunds Assets acquired under operating leases Property and equipment acquired under capital leases Property and equipment acquired under finance leases Property and equipment acquired under build-to-sult arrangements 768 (668) (7,449) (337) (7,686) (351) 10,317 32,173 854 381 194 (1,184) 10,615 $ 3,641