Insert a digit to make numbers that are divisible by 15 if it is possible
89…0

1 or 4 or 7

Step-by-step 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

the two may have that, even a breakdown is probably offered