function calc () {
				var a=0,b=0,answer=0;
				a = document.getElementById('num1').value;
				b = document.getElementById('num2').value;
					if (document.getElementById('rad1').checked) {
						answer = parseFloat(a) + parseFloat(b);
						document.getElementById('answer').value = answer;
					}

					if (document.getElementById('rad2').checked) {
						answer = parseFloat(a) - parseFloat(b);
						document.getElementById('answer').value = answer;
					}

					if (document.getElementById('rad3').checked) {
						answer = parseFloat(a) / parseFloat(b);
						document.getElementById('answer').value = answer;
					}

					if (document.getElementById('rad4').checked) {
						answer = parseFloat(a) * parseFloat(b);
						document.getElementById('answer').value = answer;
					}
			}