Interest
costs are a part of the cost calculation with the engineering formula.
They consider the costs that have to be paid back to the bank for borrowing the
money. Normally, the
interest is indicated as a percentage of the borrowed sum per year.
In reality, it is
calculated monthly on the base of the actual residual debt. So, it becomes less
from month to month. In the last month it is nearly zero. Taken as the grand
average, interest is calculated over half of the borrowed sum.
Thus, we can
approximately calculate the interest costs with
