The Principal remaining after the first month is P 1 = ( 1 + r ) P − c {\displaystyle P_{1}=(1+r)P-c} i.e. the initial amount has increased less the payment.
Põhisumma, mis on alles peale esimest kuud, on P 1 = ( 1 + r ) P − c {\displaystyle P_{1}=(1+r)P-c} ehk siis algsumma on vähenenud makse võrra.