no . 159 requires that unrealized gains and losses on items for which the fair value option has been elected be reported in earnings at each reporting date . sfas no . 159 is effective for fiscal years beginning after november 15 , 2007 and is required to be adopted by the company beginning in the first quarter of fiscal 2009 . although the company will continue to evaluate the application of sfas no . 159 , management does not currently believe adoption will have a material impact on the company 2019s financial condition or operating results . in september 2006 , the fasb issued sfas no . 157 , fair value measurements , which defines fair value , provides a framework for measuring fair value , and expands the disclosures required for fair value measurements . sfas no . 157 applies to other accounting pronouncements that require fair value measurements ; it does not require any new fair value measurements . sfas no . 157 is effective for fiscal years beginning after november 15 , 2007 and is required to be adopted by the company beginning in the first quarter of fiscal 2009 . although the company will continue to evaluate the application of sfas no . 157 , management does not currently believe adoption will have a material impact on the company 2019s financial condition or operating results . in june 2006 , the fasb issued fasb interpretation no . ( 2018 2018fin 2019 2019 ) 48 , accounting for uncertainty in income taxes-an interpretation of fasb statement no . 109 . fin 48 clarifies the accounting for uncertainty in income taxes by creating a framework for how companies should recognize , measure , present , and disclose in their financial statements uncertain tax positions that they have taken or expect to take in a tax return . fin 48 is effective for fiscal years beginning after december 15 , 2006 and is required to be adopted by the company beginning in the first quarter of fiscal 2008 . although the company will continue to evaluate the application of fin 48 , management does not currently believe adoption will have a material impact on the company 2019s financial condition or operating results . liquidity and capital resources the following table presents selected financial information and statistics for each of the last three fiscal years ( dollars in millions ) : september 29 , september 30 , september 24 , 2007 2006 2005 .

	september 29 2007	september 30 2006	september 24 2005
cash cash equivalents and short-term investments	$ 15386	$ 10110	$ 8261
accounts receivable net	$ 1637	$ 1252	$ 895
inventory	$ 346	$ 270	$ 165
working capital	$ 12657	$ 8066	$ 6813
annual operating cash flow	$ 5470	$ 2220	$ 2535

as of september 29 , 2007 , the company had $ 15.4 billion in cash , cash equivalents , and short-term investments , an increase of $ 5.3 billion over the same balance at the end of september 30 , 2006 . the principal components of this net increase were cash generated by operating activities of $ 5.5 billion , proceeds from the issuance of common stock under stock plans of $ 365 million and excess tax benefits from stock-based compensation of $ 377 million . these increases were partially offset by payments for acquisitions of property , plant , and equipment of $ 735 million and payments for acquisitions of intangible assets of $ 251 million . the company 2019s short-term investment portfolio is primarily invested in highly rated , liquid investments . as of september 29 , 2007 and september 30 , 2006 , $ 6.5 billion and $ 4.1 billion , respectively , of the company 2019s cash , cash equivalents , and short-term investments were held by foreign subsidiaries and are generally based in u.s . dollar-denominated holdings . the company believes its existing balances of cash , cash equivalents , and short-term investments will be sufficient to satisfy its working capital needs , capital expenditures , outstanding commitments , and other liquidity requirements associated with its existing operations over the next 12 months. .

Question: what was the change between september 29 , 2007 and september 30 , 2006 , of the company 2019s cash , cash equivalents , and short-term investments were held by foreign subsidiaries and based in u.s . dollar-denominated holdings , in billions?
Program: subtract(6.5, 4.1)
Answer: 2.4