How to add blank field where there is no match

[Mula]

I have two columns of sorted numbers, which don't match sometimes. I would like to put a blank cell in the column where there is no match to a number, so that all matches are in the same rows. Please see the attachment. Can you please help me?

[NBVC]

The easiest way would be to add a temporary helper column.

So in column C add formula:

=IF(ISNUMBER(MATCH(A1,B:B,0)),A1,"") and copy it right down the list...

Then copy this whole column and go to B1, then Edit|Paste Special and select Values....

Then delete the temporary column.

[Mula]

thanks a lot. Do you know a way to do it automatically, not manually?