关于Math.random()方法的问题？

int number = (int)Math.random()*10+5;//random number is from [0,1)
  System.out.println("the random number is:" + number);
  int guess;
  do {
   System.out.println("Pleae typpe int the number that in your mind which is from 0-100:");
   Scanner sc = new Scanner(System.in);
   guess = sc.nextInt();
   if(guess > number)
    System.out.println("the number is too big!");
   else if (guess < number)
    System.out.println("the number is too small!");
   }while(guess != number);
  System.out.println("congradulations!! you are right, the number is:" + guess);

通过多次的测试，如果我在Math.random() 后面乘以10加1，随机数就是1，加2，随机数就是2，加3，随机数就是3......加n,那么随机数就会是n。 这样子的话，随机数就不再是随机数了。。不知道问题在哪里