C - 支払いCalc。 $ 0で終わらない

Question

私は支払い計算機を作成しようとしていますが、残りの残高がマイナスで、$ 0ではないというエラーが発生しています。あなたがローンの終わりの利益のために二度、それらを充電している

int main() 
{ 
double selling, down, intRate, intBal, toBal, payment, loan, loanN, d; 
int counter, i; 

printf("Cost of item: "); 
scanf("%lf", &selling); 

printf("Down payment on item: "); 
scanf("%lf", &down); 

printf("Interest rate: "); 
scanf("%lf", &intRate); 

printf("Monthly payment: "); 
scanf("%lf", &payment); 

d= selling * 100.0; 
i = d + 0.5; 
selling = i/100.0; 

d= down * 100.0; 
i = d + 0.5; 
down = i/100.0; 

d= payment * 100.0; 
i = d + 0.5; 
payment = i/100.0; 

counter = 1; 

loan = selling - down; 

printf("--------------------------------------------------------------\n"); 
printf("Selling Price  = %8.2lf\n", selling); 
printf("Down Payment   = %8.2lf\n", down); 
printf("Amount of Loan  = %8.2lf\n", loan); 
printf("Annual Interest Rate = %8.2lf\n", intRate); 
printf("Monthly Payment  = %8.2lf\n", payment); 
printf("--------------------------------------------------------------\n"); 
printf("Pay # Old Balance Payment Interest To Balance New Balance\n"); 
printf("----- ----------- ------- -------- ---------- -----------\n"); 

while (loan > 0) 
{ 
if (loan < payment) 
{ 
    payment = loan + intBal; 
} 
printf("%5i %11.2lf %7.2lf ", counter, loan, payment); 
intBal = intRate * loan/12; 
printf("%8.2lf ", intBal); 
toBal = payment - intBal; 
printf("%10.2lf ", toBal); 
loanN = loan - toBal; 
loan = loanN; 
printf("%11.2lf\n", loanN); 
counter++; 
} 
return 0; 

Answer 1

：ここでは、コードです。このライン質問です何

intBal = intRate * loan/12;