# Calculate the sum from select multiple question

Hello Team,

Kindly assist me, I am trying to calculate a total value depending on the species of fish chosen from the group and the weight and value-filled.
Right now it’s not populating.
aPsmJkcegnRGTVvBmfTnZH.xlsx (11.2 KB)

Hi @zachzach13 and welcome to the community!

Can you share the calculation process with the community? Preferably with screenshots if you can.

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aPsmJkcegnRGTVvBmfTnZH.xlsx (11.2 KB)

@zachzach13 can you also explain the part where you are having trouble with?

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Thank you for the quick feedback,

1. Before i included the select multiple (row 32) i could get the total at row 56 and 58…but when i included the select multiple (row 32) now the sum doesn’t populate.

Do you get a NaN value?

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Not after I added the choose multiple

Can you explain this a little further?

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okay let me try and make it simple…
How can i include a sum at the end of the form depending on SPECIES CAUGHT?

If `DID YOU CATCH FISH TODAY?` question has been answered `YES`, your `SUM note` displays `NaN`

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 have possible unanswered `integer` questions depending on your `multiple choice` question.

So changing your `calculate` `Total_Weight` question to:
`coalesce(\${NPW}, 0)+coalesce(\${DW}+...`