LINUX assignments questions

I need the formula to answer these questions or the some explanations how to answer it ?

1.  Assuming a disk with 4kb blocks and 32-bits per block address, how would an i-node allocate the pointers for a 640-mb file?

2.  Assuming a disk with 4kb blocks and 64-bits per block address, how would an i-node allocate the pointers for a 640-mb file?

3.  Assuming a disk with 8kb blocks and 64-bits per block address, how would an i-node allocate the pointers for a 640-mb file?

4.  Assuming a disk with 4kb blocks and 32-bits per block address, how would an i-node allocate the pointers for a 6.4gb file?

5.  Assuming a disk with 4kb blocks and 64-bits per block address, how would an i-node allocate the pointers for a 6.4gb file?

7.  One measure of success in System Administration is server (or service) “uptime”. How much downtime would be allowed to achieve “5 nines” and “6 nines” over a period of 120 days.