This formula will do addition for me ${Quarter_1}+${Quarter_2}+${Quarter_3}+${Quarter_4} but what if I want a value if any (Quarter_1, Quarter_2, Quarter_3, or Quarter_4) of the question was answered?. I notice all the question have to be answered for calculation to effective

Hi @sophy and welcome to the community!

That is because In the ODK Form Logic, unanswered number questions are nil. That is, they have no value. When a variable referencing an empty value is used in a math operator or function, it is treated as Not a Number (`NaN`

). The empty value will not be converted to zero. The result of a calculation including `NaN`

will also be `NaN`

, which may not be the behavior you want or expect.

To convert empty values to zero, you can use either the `coalesce()`

function or the `if()`

function.

`coalesce(${potentially_empty_value}, 0)`

`if(${potentially_empty_value}=“”, 0, ${potentially_empty_value})`

In your case, you need to put `coalesce`

before every potential empty integer value. Not just before whole calculation.

You can find more information on `coalesce`

function through our community posts that have been discussed previously **here ** .

See documentation, please: ODK XForms Specification and Form Logic - ODK Docs.

@Kal_Lam might be preferable to add it (coalesce) in the Help Center articles too.