package 使用while循环计算阶乘;import java.math.*;public class 使用while循环计算阶乘 {        public static void main(String[] args) {        // TODO Auto-generated method stub        BigDecimal sum = new BigDecimal(0.0);        BigDecimal factorial = new BigDecimal(1.0);                int i = 1;                while(i <= 20)        {            sum = sum.add(factorial);            ++i;            factorial = factorial.multiply(new BigDecimal(1.0/i));        }                System.out.println("1+1/2!+1/3!+...+1/20!的计算结果等于:\n"+sum);    }}