In order to reproduce open help page:
The first possibility mentioned in the help page (“Right click in a table cell …”) is no longer valid. The function has changed quite long ago (version 4.?.?). Currently (version 7.0.3) you can turn on or off the Number Recognition via the menu: Table > Number Recognition.
I believe Seth (added to CC) has worked on this page recently, and the result of his work can be viewed at:
How does the improved help page look to you?
*** This bug has been marked as a duplicate of bug 138389 ***