When calculating borrowings, the IBRD takes the amount of the loan, multiplies it by the interest rate, and obtains a total for the interest. All the loans are added and all the interest totals. The first sum is then divided by the second to obtain the weighted average interest. This is the single-weighted borrowing cost. Recently, the IBRD has obtained the interest total by multiplying the amount of the loan by the interest and the number of years to maturity, to take into account the fact that it has loans of varying maturities. The weighted averaged interest obtained from this calculation is called the double weighted borrowing cost.