# Interest calculation,

## Keywords: interest calculation, simple Interest, compound Interest, investment, annuity, interest rates, principal

**Simple Interest**

Interest * i* for the principal

*with an interest rates of*

**P****%:**

*r*Interest coefficient * q* in case the interest rate is

**%:**

*r*Increased value of principal * P* increased with interest at the interest rate of

*%:*

**r****Compound Interest**

Value of principal ** P_{n}** after

*years with an interest rate of*

**n****r**% in case of starting principal

**:**

*P*_{0}Value of principal ** P_{n}** after

*years with an amortization rate of*

**n****r**% in case of starting principal

**:**

*P*_{0}Discount value of principal ** P_{n}** with an interest rate of

**r**%:

Increase of annuities * a* after

*years:*

**n****Investment**

Availabel amount after * n* years in case of annuity investment

*(amount, invested each year),*

**a**if the payment is at the

*of each year:*

**beginning**Availabel amount after * n* years in case of annuity investment

*(amount, invested each year),*

**a**if the payment is at the

*of each year:*

**end**Installment (annuity) of the loan * P* on an annual basis, if the repayment rate is due at the end of the year: