I don't know how to calculate the interest on coins either. I've tried to reconstruct the interest rate from code, but there are too many variables. some of the variables such as number of people active in a tribe is unknown.

@penguinpablo made an upvote calculator for HIVE.

The owner of a tribe should be able to calculate the APR simply by knowing the number of coins on the market and the number that will produced during the year. HIVE Engine says that there is 25.38 Million Meme on the market. If you mint 2.5 million Meme, then the APR is 10%.

Hive Engine Tools by @TheMarkyMark has a tool that will show what a person has made curating a token over the last 30 days. This is the second tool in the list. It shows NaN for MEME.

Maybe that's the meme!! What we are receiving from MEME isn't a number it is something greater than a number.