How to return a zero when subtrahend is blank

[OhLookAnError]

I am trying to acurately display days since opened and days since closed in calculated columns. My days since closed column which is:  

Days Since Closed = tblAccounts[Todays Date] - tblAccounts[Account Closed]

is returning this 48888 when there is no closed date. 

How can I get this to return zero if the Account closed Column is blank? 

Thanks in advance! 

[tamerj1 · Accepted solution]

Hi @OhLookAnError 
Please try

Days Since Closed =
tblAccounts[Todays Date]
    - COALESCE ( tblAccounts[Account Closed], tblAccounts[Todays Date] )

[OhLookAnError]

Worked, Thank you! 

[FreemanZ]

try this:

Days Since Closed = 

VAR _duration =

tblAccounts[Todays Date] - tblAccounts[Account Closed]

RETURN

IF(

    [Account closed Column]=BLANK(),

    0,

   _duration 

)