4 factorial of number

# ************While****************
echo enter the number
read n
i=1
fact=1
while [ $i -le $n ]
do
    fact=`expr $fact \* $i`
    i=`expr $i + 1`
done
echo factrial is $fact

# ************Until*******************
echo enter the number
read n
fact=1
i=1
until [ $i -gt $n ]
do
    fact=`expr $fact \* $i`
    i=`expr $i + 1`
done
echo factrial is $fact

# ***************For*******************