Do you really need the calculations all in the same record? If not, the easiest way is to just convert your field into a linked record field, and when you are prompted for which table to link to, create a new table called Calculations.
Then, in your new Calculations table, you can add a field of type “Count”.
Thanks for your help on the above @ScottWorld - I have another question. Is there a way I can tally occurrences with some sort of conditional? e.g. If I have Blue1, Blue2, Blue3, Red, Yellow1, Yellow2.
Can I somehow tally the total number of Blues even if they are not identical record names? TIA.