NOT

The NOT function returns the opposite of the boolean value of a specified expression.

NOT(any-expression)

any-expression: An expression to be tested. any-expression can contain anything as long as the expression evaluates to a boolean value. If the expression evaluates to a number, 0 is considered to be FALSE, and any other number is considered to be TRUE.

Examples
=NOT(0) returns TRUE because 0 is interpreted as FALSE. =OR(A9, NOT(A9)) always returns TRUE because either A9 or its opposite will always be true. =NOT(OR(FALSE, FALSE)) returns TRUE because neither argument of the logical OR is true.

Examples

=NOT(0) returns TRUE because 0 is interpreted as FALSE.

=OR(A9, NOT(A9)) always returns TRUE because either A9 or its opposite will always be true.

=NOT(OR(FALSE, FALSE)) returns TRUE because neither argument of the logical OR is true.