Though the Instagram sale got a lot of press for its big $1 billion price tag, when all is said and done Facebook will only pay $715 million in cash and stock for the photo-sharing app, according to a Security and Exchange Commission filing from today. The 10-Q states that Instagram will sit in its accounting for $512 million. How do we get $715 million then? The Next Web's Alex Wilhelm does the math for us:

That figure was arrived at by adding the $300 million in cash that Facebook promised, and the price of 12 million vested shares of Class B common stock. This stock was given to “non-employee stockholders” – investors, it would seem – but not the staff itself.

Adding to the tally, Facebook has issued 11 million un-vested shares to Instagram’s employees, a pool that includes its founders. These shares will vest over a three year period. They have an “aggregate fair value of $194 million.” Adding the two together, Facebook’s final payment for Instagram totals $715 million.

$194 + $521 = $715 million.

The value of the purchase has been in-flux ever since Facebook went public because of the promised shares that came along with the cash. After the first day of trading for Facebook, the price was already well below the billion mark at $977 million. Now that the deal has closed, the final price wasn't a nice round billion, but $715 million isn't bad either.