Calculation formula of real interest rate of revolving credit

There are two formulas for calculating the real interest rate of revolving credit. The term of the first loan is several years: actual interest rate = annual interest rate/actual available loan amount × 100%= loan amount× I/loan amount *( 1-i)=i/( 1-i). Where I is the nominal interest rate. 2. Calculation formula of the real interest rate when the loan term is less than one year: the real interest rate = annual interest rate/actual available loan amount × 100%= loan amount ×i/ loan amount × (1-i/12n) = i/* (1-i). In order to maximize the benefits.