Dragging formula to add two columns, but need to show blank when other cell is blank

Evening all -

I'm new to the forum and a standard user in excel, certainly not advanced. I am having an issue where I have the following:

A5 = 50.00 B5 = A5
A6 = - aka 0 B6 = B5+A6

Hope the above makes sense. I've tried a few formulas online that I have found online, but no success. When I have 0 entered in A6 I am getting the value of B5 in cell B6. I'd like to get that to show 0 until there is a value in A6.

Is this possible or would I need to manually drag the formula "=B5+A6" down each time to cells in column B?

Originally Posted by alansidman

In B6 type =IF(ISNUMBER(A6),B5 +A6,0)

Thank you for your reply. If I have $50.00 in B5 and in A6 I have $0.00 then B6 is showing $50. Only if I delete any values in A6 will the formula show correctly. However, I need to show $0 in A6 for budgeting purpose.

Originally Posted by alansidman

=if(a6=0,0,if(isnumber(a6),b5+a6,0))

Awesome! This worked perfect! Thank you so much.