Add number based on dropdown

Hi All,

I am relatively new to, but am looking for some help please.

Within the board I have created I am looking to auto-populate a number column with a specific set of numbers based on drop-down choice selected.

the background to this is that each dropdown choice has a priority number and I would like the priority number populated automatically if possible. I understand this would mean allocated a value to each dropdown somewhere.

Anyone able to help?