Answer:
1 or 4 or 7
Explanation:
The number is divisible be 15, that means it is divisible as by 5 and as by 3
(5*3=15). The number is divisible by 5 if the last digit is 0 or 5.
In our case the last digit is 0 so the number is divisuble by 5 anyway.
The number is divisible by 3 if the sum of its digits is divisible by 3.
The sum of digits is 8+9 =17 . 17 is not divisible by 3, however 18,21 or 24 are divisible by 3
So instead ... 1 ( to get sum 18), or 4 ( to get sum 21) or 7 (to get sum 24) can be written