function checkCaptcha() {
	if (answer == document.getElementById("captcha").value) {
		return true; // answer is right
		} else {
			if (answer == "") { // answer is not set
				console.log("No answer entered.");
				document.getElementById("check").innerHTML="Please answer the question.";
				return false;
				}
			document.getElementById("check").innerHTML="Incorrect answer.";
			errors++;
			console.log("errors: " + errors);
			if (errors > 3) {
				document.getElementById("check").innerHTML="Too many incorrect answers.";
				document.getElementById("register").disabled = true;
				document.getElementById("register").value="Disabled";
				return false;
				} else {
					document.getElementById("check").style.color="red";
					return false; // answer is wrong
					}
			}
  }