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Returns the hour for a given time value. The hour is returned as an integer between 0 and 23.
HOUR(Number)
Number, as a time value, is a decimal, for which the hour is to be returned.
HOUR() returns the integer part of the hour.
HOUR(NOW()) returns the current hour
HOUR(C4) returns 17 if the contents of C4 = 17:20:00.