//formatcurrency to GBP
function formatGBP(number){

var decimalPos;
var leftPart = number.toString();
var orgLeftPart = "";
var digitCount = 0;
var digitChar = "";
var decimalPart = "";

decimalPos = leftPart.indexOf(".");
if (decimalPos!==-1) {
decimalPart = leftPart.substring(decimalPos);
leftPart = leftPart.substring(0,decimalPos);
}

decimalPart = decimalPart.substring(0,3);

orgLeftPart = leftPart;
leftPart="";
for (var x=orgLeftPart.length-1;x!=-1;x--) {

digitCount = digitCount + 1;
digitChar = orgLeftPart.substring(x,x+1);
if (digitCount==3) {
digitCount=0;
digitChar = "," + digitChar;
}
leftPart = digitChar + leftPart;

}
if (leftPart.substring(0,1)==",") {leftPart=leftPart.substring(1);}

return("£" + leftPart + decimalPart);

}


//strip number
function v_number(number){
var digits="0123456789.£";
if (number=="£") {return false;}
if (number.length==0) {return false;}
for (var i=0;i<number.length;i++){if (digits.indexOf(number.substring(i,i+1))==-1 && number.substring(i,i+1)!="."){return false;}}
if (number<0) {return false;}
return true;
}

//format number
function formatNumber(number){

var decimalPos;
var leftPart = number.toString();
var orgLeftPart = "";
var digitCount = 0;
var digitChar = "";
var decimalPart = "";

decimalPos = leftPart.indexOf(".");
if (decimalPos!==-1) {
decimalPart = leftPart.substring(decimalPos);
leftPart = leftPart.substring(0,decimalPos);
}

decimalPart = decimalPart.substring(0,3);

orgLeftPart = leftPart;
leftPart="";
for (var x=orgLeftPart.length-1;x!=-1;x--) {

digitCount = digitCount + 1;
digitChar = orgLeftPart.substring(x,x+1);
if (digitCount==3) {
digitCount=0;
digitChar = "," + digitChar;
}
leftPart = digitChar + leftPart;

}
if (leftPart.substring(0,1)==",") {leftPart=leftPart.substring(1);}

if (leftPart == "NEGATIVE FIGURE") {leftPart = "No figure available";}

return(leftPart + decimalPart);

}

//calc break even

function calculateBreakEven() {

var frm=document.forms.frmBreakEven;
var intX=frm.entered_sales.value; 
var intY=frm.entered_costofsale.value;
var intF=frm.entered_projectedexpenditure.value;
var errorMessage="";
if (!v_number(intX)) {errorMessage+="Sales,\n";}
if (!v_number(intY)) {errorMessage+="Cost of Sales,\n";}
if (errorMessage.length!=0) {alert("These values are invalid:\n\n"+errorMessage+"\nPlease correct these and\ntry again.");return false;}
else if (!v_number(intF)) {alert("Please now enter a figure for Projected Fixed Expenditure.");return false;}

if (parseFloat(intX) < parseFloat(intY)) {alert("Error - Cost of sales is higher than sales.");return false;}

var intS=0; 

intS = (intF * (intX / (intX - intY)));

frm.result_salesrequired.value=formatGBP(intS);

return false;
}

function checkFields() {
var frm=document.forms.frmBreakEven;
var intX=frm.entered_sales.value 
var intY=frm.entered_costofsale.value 
var intZ=frm.entered_expenditure.value 

var intD=0; // Result - net profit / loss

	if (parseFloat(intX) < parseFloat(intY)) 
	{
		alert("Error - Cost of sales is higher than sales.");
		frmBreakEven.entered_costofsale.focus();
	}
	else
	{

		intD = (intX - intY - intZ);
		frm.result_profit.value = formatGBP(intD);
	}
}


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