How to return a blank formula cell if the reference is blank?

[waybomb]

Hi All

Let's say I have a formula in cell c1. It references a number input into
cell a1, and does some math with that cell and a fixed number in cell b1.

Now what I want to do is have cell c1 be blank if cell a1 is also blank. But
when a number is entered into cell a1, I want the resultant formula answer to
be displayed in cell c1.

What do I add to my formula to do so, and where do I put it?

Thanks - y'all are a big help!

 

[Gary''s Student]

Say C1 used to contain:
=A1+B1
replace with:
=IF(A1="","",A1+B1)

so if A1 is blank, then so will C1

 

[Bernard Liengme]

=IF(ISBLANK(A1),"", your-formula)

For example: =IF(ISBLANK(A1),"", A1/B1+3)
best wishes