function rechnen() { 
var eins = 0;
var zwei = 0;
var drei = 0;
var vier = 0;
var fuenf = 0;
var sechs = 0;
var sieben = 0;
var acht = 0;
var achtb = 0;
var neun = 0;
var zehn = 0;
var elf = 0;
var zwoelf = 0;
var dreizehn = 0;

if (document.getElementById("a1").checked == true) { var eins = document.getElementById("preis_1").value; }
if (document.getElementById("a2").checked == true) { var zwei = document.getElementById("preis_2").value; }
if (document.getElementById("a3").checked == true) { var drei = document.getElementById("preis_3").value; }
if (document.getElementById("a4").checked == true) { var vier = document.getElementById("preis_4").value; }
if (document.getElementById("a5").checked == true) { var fuenf = document.getElementById("preis_5").value; }
if (document.getElementById("a6").checked == true) { var sechs = document.getElementById("preis_6").value;  }

if (document.getElementById("a7").checked == true) { var sieben = document.getElementById("preis_7").value; }
if (document.getElementById("a8").checked == true) { var acht = document.getElementById("preis_8").value; document.getElementById("fotoupload").style.display = "block";}
else { document.getElementById("fotoupload").style.display = "none";}
if (document.getElementById("a8b").checked == true) { var achtb = document.getElementById("preis_8b").value; document.getElementById("fotoupload").style.display = "block";}
else { document.getElementById("fotoupload").style.display = "none";}
if (document.getElementById("a9").checked == true) { var neun = document.getElementById("preis_9").value; }
if (document.getElementById("a10").checked == true) { var zehn = document.getElementById("preis_10").value; }
if (document.getElementById("a11").checked == true) { var elf = document.getElementById("preis_11").value; }
if (document.getElementById("a12").checked == true) { var zwoelf = document.getElementById("preis_12").value; }
if (document.getElementById("a13").checked == true) { var dreizehn = document.getElementById("preis_13").value; }
var endpreis = (eins)*1 + (zwei)*1 + (drei)*1 + (vier)*1 + (fuenf)*1 + (sechs)*1 + (sieben)*1 + (acht)*1 + (achtb)*1 + (neun)*1 + (zehn)*1 + (elf)*1 + (zwoelf)*1 + (dreizehn)*1;
document.getElementById("betrag").innerHTML = endpreis + ' €';
document.getElementById("betrag2").innerHTML = endpreis + ' €';
document.getElementById("betrag3").value= endpreis ;

}