UNIX for Dummies Questions & Answers

echo Enter a number
read no
i=1
ans=0
while [ $i -le 'expr $no / 2' ]
   do
       if [ 'expr $no % $i' -eq 0 ]
       then
          ans='expr $ans + $i'
       fi
       i='expr $i + 1'
done
if [ $no -eq $ans ]
then
echo $no is perfect
else
echo $no is NOT perfect
fi

'expr $no / 2'

$(expr $no / 2)

if [ 'expr $no % $i' -eq 0 ]

if [ `expr $no % $i` -eq 0 ]

$ echo `expr 4 / 2`
2
$ echo 'expr 4 / 2'
expr 5 / 2
$ echo $(expr 4 / 2)
2