[O] empty cells in columns should be left emtpy when manipulating columns

[Uwe Brauer]

Please consider this

| 3.25 | 0.4875 |
|      |     0. |
| 2.25 | 0.3375 |
#+TBLFM: $2=$1*0.15

How can I avoid the entry 0.  ?

I could insert **

Giving

| 3.25 |  0.4875 |
|   ** |  #ERROR |
| 2.25 |  0.3375 |
#+TBLFM: $2=$1*0.15

But this is cumbersome, any other possibilities?

Thanks

Uwe Brauer