Some applications of financial mathematics in solving economic problems

The paper presents a formula for increasing by simple percentages, considered the definition of the period of accrual of simple interest, the definition of the annual period for a given number of days. And also, the concepts of ordinary simple percentage, exact prime percentage, approximate time are considered. In addition, examples of accrual of simple interest were solved, the accrual period was calculated, simple variable rates, reinvestment on simple interest were considered. The formula of increment on compound interest and the formulas for doubling the amount are used.