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Returns the second for the given time value. The second is given as an integer between 0 and 59.
SECOND(Number)
Number, as a time value, is a decimal, for which the second is to be returned.
SECOND() rounds to the nearest second, instead of returning the integer part of the seconds.
=SECOND(NOW()) returns the current second
=SECOND(C4) returns 17 if contents of C4 = 12:20:17.