We found that interest *4 is a double digit, that is, interest can only be 1 or 2, but interest = interest *4 is a single digit, so interest must be even, so interest =2, multiplied by 4 to get 2 digits, including 3 and 8. If interest =8, interest =28, multiplied by 4 becomes three digits, which is inconsistent with the meaning of the question, so interest =3.

23+23+23+23=92