Formula Syntax

Formula Syntax

Can anyone help me get the syntax right for this formula?

I have 4 fields.

field1 is true/false
field2 is a number
field3 is a number
field4 is a formula

I want field4 to perform this function: If field1 is false, then field4 = (field2 * field3). If field1 is true, then field4 is null.

Thanks,
Tom