Hey nccomposer,
Thanks for visiting Apple Support Communities. I see that you’re having issues opening up the Numbers app on your Mac and I’d like to help. I use the Numbers app pretty often, so I can understand your concern.
Try deleting and reinstalling the Numbers app. Here’s how you delete the app on your Mac: How to delete apps on your Mac
Once deleted, go to the App Store and install the Numbers app again.
If the issue persists, try quitting the Numbers app and re-open the app while holding down the 'Shift' key on your keyboard. Holding the Shift key while starting an application temporarily disables restoring the app's saved state, such as opened windows and documents. For more information about this, check out this article: Automatically re-open windows, apps, and documents on your Mac
Let me know if that helps.
Cheers!