Principal and interest on any amounts advanced by the Bank under any Letter of Credit are payable on demand and shall be computed on the basis of a 360-day year for the actual number of days elapsed. In computing interest, the date of the making of any Credit Extension shall be included and the date of payment shall be excluded; provided, however, that if any Credit Extension is repaid on the same day on which it is made, such day shall be included in computing interest on such Credit Extension.