//计算20的阶乘

BigInteger lotteryOdds = BigInteger.valueOf(1);

//相当于 new BigInteger("1"),就是新建一个BigInteger值为1的对象。

for (int i = 1; i <= 20; i++){

lotteryOdds = lotteryOdds.multiply(BigInteger.valueOf(i + 1));

System.out.println(lotteryOdds);

}

//add

 bigInteger1=bigInteger1.add(bigInteger2);

 System.out.println(bigInteger1);


 //subtract

 bigInteger1=bigInteger1.subtract(bigInteger2);

 System.out.println(bigInteger1);


 //multiplay

 bigInteger1=bigInteger1.multiply(bigInteger2);

 System.out.println(bigInteger1);


 //divide

 bigInteger1=bigInteger1.divide(bigInteger2);

 System.out.println(bigInteger1);