Code For Gas Usage Calculator

function d(){
  var a = document.form1.miles.value;
  var b = document.form1.gas.value;
  var c = document.form1.days.value;
  var cost = document.form1.cost.value;
  mpg=a/b;
  gpd=b/c;
  mpg= Math.round(mpg*10)/10;
  gpy=gpd*365;
  co=gpy*19.36;
  cpy=gpy*cost;
  gpd= Math.round(gpd*1000)/1000;
  gpy= Math.round(gpy*10)/10;
  cpy= Math.round(cpy*100)/100;
  co= Math.round(co);
  document.form1.results.value="Your car is getting "+mpg+" miles per gallon. On the average you use "+gpd+" gallons per day. At that rate of consumption you will burn "+gpy+" gallons per year at a cost of $"+cpy+" per year. In addition, that produces "+co+" pounds of CO2 in one year.";
}
// End -->
</script>

<form name="form1">
<b>Miles Traveled:</b>  
<input type="text" size="8" name="miles">   
<b>Gallons of Gas:</b>  
<input type="text" size="6" name="gas"><br><br>
<b>Cost of Gas:  $</b>
<input type="text" size="4" name="cost">  
<b>Days Between Fill-Ups:</b>  
<input type="text" size="6" name="days"><br><br>
<input type="button" value="Calculate" onclick="d()"> <input type="Reset" value="Clear"><br><br>
<b>Results</b><br>
<textarea name="results" rows="5" cols="55" wrap style="border-width:0;overflow:hidden"onfocus="this.blur()">
</textarea>
</form>