Question

编写一个JAVA程序,求1!+2!+3!+......+10!的结果，并将结果输出

Answer 1

效率阿。。。如果超过17的阶乘，就要用long了

public class Factorial {

public static void main(String[] args) {

int sum = 0;
int fac = 1;

for(int i = 1; i <= 10; i++){
fac = i * fac;
System.out.println(i + "! = " + fac);
sum += fac;
}

System.out.println("1!+2!+3!+...+10! = " + sum);
}
}

－－－－－－－－－－－－－－
1! = 1
2! = 2
3! = 6
4! = 24
5! = 120
6! = 720
7! = 5040
8! = 40320
9! = 362880
10! = 3628800
1!+2!+3!+...+10! = 4037913

Answer 2

笨办法，但是好理解。
public class test
{
public static int jiecheng(int n)
{
int sum = 1;
for (int i = 1; i <= n; i++)
{
sum = i*sum;
}
return sum;

}

public static void main(String [ ] args)
{
test t = new test();

int all=0;
for(int i=1;i<=10;i++)
{
all=all+jiecheng(i);
System.out.println("总数是："+all);
}
//System.out.println("总数是："+all);
}
}

Answer 3

public class Factorial {
private int result = 1;
public int factorial(int number){
if(number==1)
return result;
else
{
result = number*factorial(number-1);
return result;
}
}
public static void main(String[] args) {
Factorial f = new Factorial();
System.out.println(f.factorial(10));
}
}

Answer 4

参考这个 计算阶乘的和

Answer 5

for循环就可以,