Calculating factorial using bash one liner

 

I was trying to get the factorial of a number in bash,it's an easy program obviously ,using loop I can do this,for example

#!/usr/bin/bash
echo "Enter number"
read number

result=1
for((i=1;i<=number;i++))
        do
                result=$(($result*i))
        done
echo "The factorial of $number is $result"

Then I tried to find some one liners,I mean bash is famous for one liners ,using seq and bc it worked just fine.

sourav@LAPTOP-HDM6QEG8:~$ num=5
sourav@LAPTOP-HDM6QEG8:~$ seq -s "*" 1 $num | bc
120

Using $(( it also worked like it should

sourav@LAPTOP-HDM6QEG8:~$ echo $((`seq -s "*" 1 $num`))
120

However when I am trying to use expr I am not able to do it.

sourav@LAPTOP-HDM6QEG8:~$ expr `seq -s " * " 10`
expr: syntax error: unexpected argument ‘0’

I thought since * is an universal symbol may be I should escape it,but it still does not work

sourav@LAPTOP-HDM6QEG8:~$ expr `seq -s " \* " 10`
expr: syntax error: unexpected argument ‘\\*’

However I am able to perform the summation though like this

sourav@LAPTOP-HDM6QEG8:~$ expr `seq -s " + " 10`
55

So why I am getting an error when trying to get the multiplication of a series using expr,can someone explain please??