Which of the following is one of the 4 basic rules for calculating loan payments and balances?

1. Interest owed in each payment = applicable interest rate times outstanding principle balance
2. The initial outstanding principle balance = the initial contract principle specified in the loan agreement
3. The principle amortization in each payment = the total payment interest owed
4. The outstanding principal balance after each payment = the previous outstanding principle balance principle paid down in the payment
5. All of the above are one of the 4 basic rules