function calculate() {
	var a = document.getElementById("a").value;
	var b = document.getElementById("b").value;
	var n = document.getElementById("n").value;
    var maxsigdig = Math.max(sigdig(a),sigdig(b),sigdig(n));
	var area;
	if (a != "" && b != "" && n != "") {
		a = parseFloat(a);
		b = parseFloat(b);
		n = parseFloat(n);
		area = ((Math.pow(b,n+1))/(n+1)) - ((Math.pow(a,n+1))/(n+1));
		document.getElementById("area").innerHTML = "area: " + area;
	}
}