function Updatevolume(number) {

var q = document.calc.diameter1.value;
var ss = document.calc.straightside.value;
var ind = document.calc.headtype.selectedIndex;
var headconst = document.calc.headtype.options[ind].value;
var tankgal = q * q * 0.0034 * ss;
var headgal = q * q * q * headconst;

var headlit = headgal / 0.2642;
var tanggal = headgal + tankgal;
var flooded = headgal + headgal + tankgal;

var tanklit = tankgal / 0.2642;
var tankgal=Math.round(tankgal*10)/10;
document.calc.tankgallons.value = tankgal;

var tanklit =Math.round(tanklit*10)/10;
document.calc.tankliters.value = tanklit;

var headgal=Math.round(headgal*10)/10;
document.calc.headgallons.value = headgal;

var headlit =Math.round(headlit*10)/10;
document.calc.headliters.value = headlit;

tanglit = tanggal / 0.2642;
var tanglit =Math.round(tanglit*10)/10;
var tanggal = Math.round(tanggal*10)/10;
document.calc.headtangentgallons.value = tanggal;
document.calc.headtangentliters.value = tanglit;

floodedlit = flooded / 0.2642;
var floodedlit =Math.round(floodedlit*10)/10;
var flooded = Math.round(flooded*10)/10;
document.calc.headfloodedgallons.value = flooded;
document.calc.headfloodedliters.value = floodedlit;

}