Numbers - General Questions

What is the smallest digit that can replace * so that 658*1 is divisible by 9?

What is the unit digit of 70⁷⁰³?

What is the unit digit of 67⁶⁴⁷?

What is the smallest digit that can replace * so that 8*627 is divisible by 9?

7443 is divisible by which of the following?