Numbers Constantly Crashing

Have you tried restarting your Mac?

If that doesn't work you could try holding down the shift key while you restart.

If all that still doesn't work then you could try uninstalling Numbers (Launchpad, hold down the option key until the icons wiggle and click the x by Numbers) then reinstall from the Mac App Store.

SG

I would submit that the crash is caused by a corrupt file or corrupt preferences.

If you have a bunch of files open, then try to open Numbers, save them one-at-a-time (hopefully before it crashes) and close the file you just saved. Once they are all closed, try opening those file one at a time.

IF you identify the offending file, then try duplicating the file (in the finder). See if the duplicate will also cause Numbers to crash. If it does, then remove half of the sheets.

Based on what you learn from this, you have now isolated the problem, in the file to one half of the document. If it crashes, then the problem is in the remaining half. If it doesn't crash, then delete the document and duplicate the original document again.

Write back with your findings