Equation that looks at one cell unless its empty, then defaults to another

[RodneyW]

I need a formula that will be placed in Q9 then modified to be placed in Q10, Q11 and so on. It will be a modification of this:

=P9+(P9*$P$7)

The value in P7 is a predicted interest rate used to predict revenue during a specific period and is used to look ahead for many years. After the period is over, I no longer want it to use the predicted rated, rather use the actual rate which will be posted in R9 (for the Q9 equation, R10 for the Q10 equation and so on).

I think what I need is something like this =P9+(P9*$R9) but then understand that if R9 (R10 etc) is empty it defaults to $P$7

Thanks in advance

 

[Cubist]

Try:

=P9*(1+IF(R9="",$P$7,R9))

 

[RodneyW]

Try:

=P9*(1+IF(R9="",$P$7,R9))

Thank you, that works well