Shell Programming and Scripting

read num
num={1..5}  
while [ "$num" -le 5 ]
do
f=[ "$num" * "$num" ]
done
echo f

line 5: ${1..5} bad substitution
line 6: integer expression expected

f=1

for num in {1..5}
do
  f=$(( $f * $num ))
done

echo $f

do f=$(( "$f" * "$num" ))
done
echo "$f"

line 8: "1" * "1": syntax error: operand expected (error token is " "1" *  "1" ")

i=1

for fact in `seq 1 5`
do
          i=$(( $i * $fact ))
done

  echo $i

my $i = 1;
my $result = 1;
$result *= $i++ while ($i <= 5) ;
print "Value : $result\n";

f=1

for fact in {1..5}
do
      let f*=fact
done

echo "Factorial of 5 is:$f"