function makeQuiz(min, max, op){
  var v1 = makeRandom(min, max);
  var v2 = makeRandom(min, max);
  var str = "";
  str += v1 + " " + op + " " + v2 + " =\n";
  str += "sa:\n";
  //正答を作る
  var answerArray = [];
  var answer = calc(v1, v2, op);
  answerArray.push(answer);
  str += answer + "\n";
  //誤答を作る
  var dummyCount = 0;
  var endlessLoopDetector = 0;
  while(dummyCount < 3){ 
    var v3 = makeRandom(min, max); 
    var v4 = makeRandom(min, max); 
    var dummyAnswer = calc(v3, v4, op); 
    if(answerArray.indexOf(dummyAnswer) == -1){ 
      str += dummyAnswer + "\n"; 
      answerArray.push(dummyAnswer); 
      dummyCount++ 
    }else{ 
      if(endlessLoopDetector++ > 10**3)break;
    }
  }
  return str;
}

function calc(a, b, op){
  switch(op){
    case "+": return a+b;
    case "*": return a*b;
  }
}

function makeRandom(m1, m2){
  max = Math.max(m1, m2);
  min = Math.min(m1, m2);
  return Math.floor(min + (max - min + 1) * Math.random());
}

function makeQuizN(min, max, op, n){
  var qArray = [];
  for(var i = 0; i &lt; n; i++){
    qArray.push(makeQuiz(min, max, op));
  }
  return qArray.join("\n");
}