How does a farmer who borrows just under £70,000 from a building society in 1989 and makes repayments at irregular intervals of sums adding up to over £73,000 end up seven years later owing the society more than £198,000?
That question is at the core of the trauma which led to the eviction on Wednesday of the family of the late Milo Murphy from their Co Waterford house and farm.
The answer appears to lie in the heavy surcharges the society applied once the scheduled repayments went into arrears, as well as multiple legal charges, all of which came on top of the standard interest charges and built up the outstanding balance on the account at a fearsome rate.
The family's financial adviser, Mr Martin O'Sullivan, calculates that the penalties and surcharges applied by the Irish Nationwide Building Society from the time the repayments first fell into arrears have amounted to over £97,000.
At a public meeting in Clonea on Wednesday night he gave examples of the penal compound interest rates applied to repayments in arrears during several sample years since the loan was taken out.
In 1992, for example, the surcharge rate applied was around 20 per cent, when the standard interest rate applied by financial institutions would have been about 15 per cent, he said.
In 1993 the surcharge rate applied was 23 per cent, when the standard rate would have been 13.75 per cent. And in 1994 the surcharge rate applied was 17.5 per cent, compared to a general rate of 10.75 per cent.
It was admitted that the late Mr Murphy had allowed the repayments to fall very rapidly into arrears. In the first three years he had lodged only very small sums, which fell far short of the schedule of required repayments.
This was the crucial mistake or neglect which prompted the society to initiate proceedings and also brought into play the system of severe and cumulative surcharges, plus ongoing legal costs, which sent the account spiralling.
The successive mortgage account statements, which have been seen by The Irish Times with the family's consent, indicate the scale and speed at which the debt accumulated.
By the end of 1991, when only about £405 had been repaid on the account, the balance outstanding on the loan had grown to £97,661, and arrears on the account were stated to be over £28,000. Even at that stage the surcharge interest on the repayments in arrears, plus legal costs, had added almost £6,000 to the balance outstanding.
By the end of 1992 the arrears were recorded as nearly £51,000 and the balance outstanding had grown to over £121,000.
At the end of 1993, in spite of more substantial repayments, the arrears were nearly £83,000 and the balance almost £153,000. In 1994, when Mr Murphy became very ill and an administrator was appointed as sole guardian, the balance outstanding grew to over £154,000, in spite of repayments of around £29,000 being made.
In 1995, during which repayments totalling some £43,000 were made after land was sold, the outstanding balance was down to about £135,000.
However, in the first half of 1996, as repayments fell away again, the balance rose to £153,000.
No written statements of the account have been available for examination concerning the period since then, but legal costs and surcharged interest have clearly escalated, and the family's representatives say they have been told recently the current outstanding balance is more than £198,000.
The representatives say "reasonable" settlement offers have been rejected by the society. One figure quoted as proposed was a schedule of repayments of some £13,000 a year.
The Murphys' legal representatives, who have been involved only during the past two years, say they are still examining why substantial life assurance policies on Mr Murphy were allowed to lapse before his death on November 15th, 1995, as premiums remained unpaid from about mid-1994 onwards.
All in all, however, this financial saga carries a salutary message for all mortgagees who allow repayments to slip into arrears, opening the possibility that some mortgagers may then apply the full rigours of onerous surcharges, plus unpredictable and generally substantial legal costs.