Convert time to milliseconds in Excel

I am trying to convert something in the following format to seconds.

Across the first row I have: Year, Month, Day, Hour, Minute, Seconds Sec开发者_JS百科ond row I have for example: 2011, 07, 06, 20, 37, 06

How would I convert this to a single cell that specifies the number of total seconds that number is equal to. Keep in mind that different months have different number of days.

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Lets say you have your values in row 2 and your reference date in G1, then this formula

=((DATE(A2,B2,C2)+TIME(D2,E2,F2))-G1)*24*60*60

should give you the desired result