function isNumber(number){

	if (number.length == 0) return false;

	var number_format = "0123456789";
	ok = 0;
	
	for (i=0; i<number.length; i++)
		{
			if(number_format.indexOf(number.charAt(i))>=0)
				{
					ok++
				}
		}
	
	if (ok == number.length) {return true}
	else {return false}	
		
}