function formatNumber( num, decimalPlaces, decimalPoint, thousandsPoint ) {
// Converts a number into a string with the specified formatting
	var strng = "", s1;
	var i = num;
	
	if( decimalPlaces == null )
		decimalPlaces = 2;
		
	if( decimalPoint == null )
		decimalPoint = ".";
		
	if( thousandsPoint == null )
		thousandsPoint = ",";
	
	var decPow = Math.pow( 10, decimalPlaces );
	
	i *= decPow;
	i = Math.abs( Math.round( i ) );

	if( decimalPlaces > 0 )
	{
		strng += decimalPoint;
		s1 = ( i + decPow ).toString();
		i /= decPow;
		strng += s1.substring( s1.length - decimalPlaces, s1.length );
		i = Math.floor( i );
	}
	
	while( Math.floor( i ) >= 1000 )
	{
		s1 = Math.floor( i ).toString();
		strng = thousandsPoint + s1.substring( s1.length - 3, s1.length ) + strng;
		i /= 1000;
	}
		
	strng = ( num < 0 ? -1 : 1 ) * Math.floor( i ) + strng;
	
	return( strng );
}

function calculate_stamp_duty()
	{
		var property_value = parseInt( remove_formatting( document.stamp_duty_calc.property_value.value ) );

		if( !isNaN( property_value ) )
		{
			var stamp_duty_pc;
			
			if( property_value <= 120000 )
				stamp_duty_pc = 0;
			else if( property_value <= 250000 )
				stamp_duty_pc = 1;
			else if( property_value <= 500000 )
				stamp_duty_pc = 3;
			else stamp_duty_pc = 4;
			
			document.stamp_duty_calc.stamp_duty.value = formatNumber( Math.round( property_value * stamp_duty_pc ) / 100, 2 );
		}
	}
	
	function currency_field_lost_focus( textInput )
	{
		if( !isNaN( textInput.value ) )
			textInput.value = formatNumber( textInput.value, 0 );
	}
	
	function currency_field_gain_focus( textInput )
	{
		textInput.value = remove_formatting( textInput.value );
	}
	
	function remove_formatting( value )
	{
		return( value.replace( /,/g, "" ) );
	}