Creating Shortcuts

A period / decimal point on Apple's French keyboard requires holding down the CAP key. This is a pain when inputting numbers into Numbers. The numeric keypad attached to the keyboard has a comma instead of a period and it causes whatever number I have inputted to multiply by 100; e.g. 123,12€ becomes 12312.00€. I would like to reprogram the F19 key or the numeric keypad's comma key (or create a shortcut for one of them) so that I only need to press one key to get a period / decimal point.

This only happens in Numbers not in Excel but I would prefer to stay with Numbers if at all possible.

I was unable to create a shortcut using Preferences -- Settings -- Keyboard -- Shortcut -- App Shortcut and I could not find any step by step instructions to do it.

Apple Technical support could not help.

I would be grateful for any help.