...is a fraction the numerator of which is equal to the number of days (calculated on the basis of a 360-day year consisting of 12 months of 30 days each) from (and including) the Issue Date of the first Tranche of the Notes to (but excluding) the date fixed for redemption or (as the case may be) the date upon which such Note becomes due and repayable and the denominator of which is 360.
http://tinyurl.com/2c3ga2n

...liczba dni n w danym okresie odsetkowym, mianownikiem zaś liczba 360...
...dnia zapłaty za obligacje zakupione na n-tym przetargu, natomiast mianownik stanowi liczba 360...
...mianownik stanowi faktyczna liczba dni w okresie odsetkowym.
http://tinyurl.com/2cceo7t