Inherited formula uses multiplication strangely

In array formulas, "*" is understood to mean "and". So, it's understood to mean: =IF((Sheet1'!F7=0)AND(Sheet1'!F8=0)","",...

More specifically..

(Sheet1'!F7=0)*(Sheet1'!F8=0)

Sheet1'!F7=0 is an expression (or question) with a true or false answer.
Is F7 equal to 0, true or false.

Same for Sheet1'!F8=0

so you end up with one of the following 4 possible combinations.
(true)*(true)
(true)*(false)
(false)*(false)
(false)*(true)

Now, performing math operations on True or False values converts those to 1's or 0's.
True = 1
False = 0
So they become
(1)*(1) = 1
(1)*(0) = 0
(0)*(0) = 0
(0)*(1) = 0

So the result of
(Sheet1'!F7=0)*(Sheet1'!F8=0)
Will only be either 1 or 0.
And it will only be 1 if both expressions(questions) are TRUE.


Now the IF normally expects a True or False value in it's expression.
But that can be substituted with 1 or 0
Again, 1 = True, 0 = False

And reallly, in the IF, 0 is False and ANY other number is TRUE.


Hope that helps.

Originally Posted by Jonmo1

And reallly, in the IF, 0 is False and ANY other number is TRUE.

And that is very useful to know.

This ends up working like an AND
(Sheet1'!F7=0)*(Sheet1'!F8=0)

You could change the * to + to make it an OR
(Sheet1'!F7=0)+(Sheet1'!F8=0)

Now the results can be 0 1 or 2
0 is false, any other number is true.

Thank you, Jonmo1. That helps enormously.