click - hide/unhide column

Hi,
how can i hide/unhide columns by clicking on another one ? For example when i click on a1, b1 with its content appears, another click, it dissapears. Normaly only a1 a3 are shown.
Something like dropdown menu.

thank you

Have you looked at Grouping?

http://datanalaysistips.blogspot.com...group-and.html

THx for answers, both would work, but i have another problem. The thing i wanted to have in those hiding/unhiding rows are pictures, and i don't know how to do this, pic is allways just floating on top, either the cells are hiden, resized or whatever.

Any thoughts about this? The think i need is click - picture vissible between a1 and a2(or a3) click-hidden. I need to have "picture link" in every row and i want to dispplay them on click or double click as many as i want - so placing picture in comment wont work, cause only 1 will be vissible at a time.

Go to the properties of the image and select the "Move and Size With Cells" option. This will hide the image when the row/column is hidden.

Thank you mrice, working like charm. Now i need to add a slight modification to the formula, how can i modify it to get this result: every second row will be hiding when clicking on the row top of it. ( there will be hidden picture in hide/unhide rows - 2,4,6,8,10... by clicking on 1,3,5,7,9...