IDEA Script or Function where the result of one task is used in the next task

I kindly need assistance with an IDEA script or function where the end result in task 1 is used in task 2; Balance in Period 0 is used to get Balance in Period 1, Balance in Period 1 is used to get Balance in Period 2, Balance in Period 2 is used to get Balance in Period 3, ...
 
I am preparing a loan schedule based on amortization.
 

 
I would like to fill the blank columns as below:
a) INTEREST DUE: Interest rate/12*BALANCE of previous period
b) INTEREST PAID: IF TOTAL PAYMENT MADE IS >=INTEREST DUE, INTEREST DUE, ELSE, TOTAL PAYMENT MADE
c) PRINCIPAL REPAID: TOTAL PAYMENT MADE - INTEREST PAID
d) BALANCE: BALANCE of previous period - PRINCIPAL REPAID
 

 
Kind regards