24601.
Seems a bit convoluted alright but the explanation I got from local CU was this.
Customer borrows 1000 whilst having 500 savings.
Customer pays off the 1000 whilst not touching the 500 savings.
So when customer has loan paid off they are 500 (ahead) and can put the loan repayment amount to savings , so next time they require funds they don,t need to borrow.
Nice idea , and given the amount Cu,s have on deposit ,it seems to work.
Its a far cry from Mr Bank, who stretch peoples finances to the limit