|If you don't mind a keyboard short cut, look here:|
F5 ALT+s k Enter CTRL+ – u Enter
If you want a formula...
This will work for data in B1:B12 when placed in C1 and dragged (drug?) down. Modify it to fit your needs.
I can not take credit for writing it...merely for finding it via Google:
This is an array formula that must be entered with Ctrl-Shift-Enter
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.