QLIK SENSE distinct count with a sum

[KimFerguson]

I need to output the balance amount only if there is only one currency in the sample. I found a way to output this condition separately for a particular currency:

NUM(Sum({$<[currency]={'810'}>} [currency_balance]), '# ##0,00')

Now I need to make sum output only when filtering is for one currency.

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[sidhiq91]

@KimFerguson  Not sure what is your requirement. If I understand correctly, if the user selects any Currency in the Filter Pane, your Sum value should change accordingly? Is  my understanding right?