Changing all "0" to "1" but keeping "10, 20, 30" etc as "10, 20, 30"

Hi All,

This may seem like a silly question and there may be a simple solution but I have the following Data:

Carton Quantity

0

1

25

40

30

168

400

1240

0

0

976

90

Is there a bit of code that I could write that would change the "0" to "1" but not change the other Zero's? There are 60,000 lines of data and using the find & replace function didn't work as it changed all of the "0" to"1".

I initially thought of using the following statement: If(A45=0,1,) but that didn't work.

Thanks!