Unless stated otherwise, the 30E/360 (German method) is used here.
If an interest tax is used in the examples, a withholding tax of 15 % is calculated.
I rounded to two decimal places by default. I round the days for whole days. Decimal years round to four decimal places.
When calculating the interest period, the first day of the deposit (or loan) is calculated and the last day of the deposit (or loan) is not calculated. From the two extreme days, therefore, only one day is counted.
If the interest rate is given monthly, semi-annually, quarterly or annually, I assume that the interest starts on the first day. So I count for a whole month, quarter, semester or year.
Unless otherwise specified, I count the one-year interest period.