function trueProcent(src, perc, dest) {
	var percField = document.getElementById(perc);
	var destField = document.getElementById(dest);
	var srcVal = parseFloat(src.value);
 if (isNaN(srcVal ) ) {
	 destField.value='';
		destField.style.color='#000';
		destField.style.fontWeight='normal';
		
		return;
	}
	var percVal = parseFloat(percField.value);
	destField.value = srcVal * (percVal/100);
	if (srcVal<500) {
		destField.value='0';
		destField.style.color='#000';
		destField.style.fontWeight='normal';
		return;
	}
	return false;
	
}

function trueProcent2(src, perc, dest) {
 var percField = document.getElementById(perc);
 var destField = document.getElementById(dest);
 var srcVal = parseFloat(src.value);

 var percVal = parseFloat(percField.value);
destField.value = srcVal/(percVal/100);
 if (isNaN(srcVal ) ) {
	 destField.value='';
		destField.style.color='#000';
		destField.style.fontWeight='normal';
		
		return;
	}
	if (srcVal<16) {
		destField.value='0';
		destField.style.color='#000';
		destField.style.fontWeight='normal';
		return;
	}
 return false;

}