What is the fortnightly payment for this mortgage?

$\text{paymentInterval}=\text{Quantity}[1,\text{Fortnight}]$

$\text{oneYear}=\text{Quantity}[1,\text{Year}]$

$\text{intervalYearFraction}=N\left[\frac{\text{paymentInterval}}{\text{oneYear}}\right] \Rightarrow 0.0383561643835616$

$\text{statedAPR}=3\frac{7}{8}\%$

$\text{EffectiveInterest}[\text{rate},\text{fraction}] \Rightarrow (\text{rate}\times\text{fraction}+1)^{1/\text{fraction}}-1$

$\text{effectiveAPR}=\text{EffectiveInterest}[\text{statedAPR},\text{intervalYearFraction}] \Rightarrow 0.0394806686994558$

$\text{interestPerInterval} = \text{effectiveAPR}\, \text{intervalYearFraction} \Rightarrow 0.00151432701860926$

Solve this equation for the payment amount, which gives the payment amount per dollar of loan per payment interval:

$\frac{\text{payment}-\text{payment} (\text{interestPerInterval}+1)^{-\text{numberOfPayments}}}{\text{interestPerInterval}}=1 \Rightarrow 0.00378224586250132$

$\text{loan}=\$\, 300000$

$\text{paymentAmount} \Rightarrow 113468$ in cents.

Here is the amortization table summarized by year:

$\begin{array}{||c|r|r|r|r||} \hline \hline \text{Period} & \text{Payment} & \text{Interest} & \text{Principal} & \text{Balance} \\ \hline \hline \text{1-26} & 29501.68 & 11472.79 & 18028.89 & 281971.11 \\ \text{27-52} & 29501.68 & 10749.35 & 18752.33 & 263218.78 \\ \text{53-78} & 29501.68 & 9996.88 & 19504.80 & 243713.98 \\ \text{79-104} & 29501.68 & 9214.20 & 20287.48 & 223426.50 \\ \text{105-130} & 29501.68 & 8400.14 & 21101.54 & 202324.96 \\ \text{131-156} & 29501.68 & 7553.43 & 21948.25 & 180376.71 \\ \text{157-182} & 29501.68 & 6672.70 & 22828.98 & 157547.73 \\ \text{183-208} & 29501.68 & 5756.67 & 23745.01 & 133802.72 \\ \text{209-234} & 29501.68 & 4803.83 & 24697.85 & 109104.87 \\ \text{235-260} & 29501.68 & 3812.76 & 25688.92 & 83415.95 \\ \text{261-286} & 29501.68 & 2781.96 & 26719.72 & 56696.23 \\ \text{287-312} & 29501.68 & 1709.78 & 27791.90 & 28904.33 \\ \text{313-338} & 29498.90 & 594.57 & 28904.33 & 0.00 \\ \hline \hline \end{array}$

In the Wolfram Mathematica code below, the "$" characters represent "\" characters that the verbatim processor does not handle correctly.

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balance = 100 QuantityMagnitude[loan];
paymentAmount =$[LeftCeiling]balance paymentPerUnit$[RightCeiling];
amort = Table[
   interest = Round[balance interestPerInterval];
   principal = Round[paymentAmount - interest];
   balance = Round[balance - principal];
   {period, paymentAmount, interest, principal, balance},
   {period, numberOfPayments}
   ];