Extract of microsoft excel help about how to use Timevalue

TIMEVALUE(time_text)The TIMEVALUE function syntax has the following arguments (argument: A value that provides information to an action, an event, a method, a property, a function, or a procedure.):

Time_text Required. A text string that represents a time in any one of the Microsoft Excel time formats; for example, "6:45 PM" and "18:45" text strings within

Formula Description (Result)
=TIMEVALUE("2:24 AM") Decimal part of a day, for the time (0.1)
=TIMEVALUE("22-Aug-2008 6:35 AM") Decimal part of a day, for the time (0.274305556)