i know its the shot in the dark on the forum but what the hell, i figure at least ONE of the asians on the board is a programmer

....so i have a programming class at school and the final project is to make an atm. the entire thing works except for option c: that states add interest into your account. a number is returned, but its an insane number. for example if i compound 500$ at 1 year for 5% it gives out like 803333 dollars.... so if anyones good at accounting and programming help?
code right now is :
if(m==1)
{
printf("you are in chequings");
printf("\nplease enter the amount of years you would like to compound for");
scanf("%f",&years);
printf("\nplease enter your interest rate");
scanf("%f",&interest);
if(newbalcheq>=5000)
{
for(i=1; i<= years*12; i=i++);
newbalance=((interest/12)*newbalcheq);
return(newbalance);
fflush(stdin);
getchar();
}
newbalcheq is the amount in the chequings account, and newbalance is SUPPOSE to be the amount of money your left with