The present paper is an attempt to: ۱- Demonstrate how money is created (by the nature of the system), and to estimate the inflation resulting from monetary factors in both usurious and non-usurious systems. Operational aspects of Islamic and non-Islamic banking systems are compared. ۲- Introduce a corrective term to be added to the multiplier of the supply of money, in order to prevent the under-estimation of the multiplier into the usurious system.