Armstrong Number

Algorithm
Step 1 : Start
Step 2 : Read number
Step 3 : Initialize 0 to sum and number to num
Step 4 : Extract lastdigit by computing number modulo 10
Step 5 : Cube the lastdigit and add it to sum
Step 6 : Divide number by 10
Step 7: Repeat steps 4–6 until number > 0
Step 8 : If sum = number then
Print “Armstrong number”
Step 8.1 : else
Print “Not an Armstrong number”
Step 9 : Stop

Program (armstrong.sh)
# Armstrong number using while loop
echo -n "Enter a number : "
read n
a=$n
s=0
while [ $n -gt 0 ]

do
r=`expr $n % 10`
s=`expr $s + \( $r \* $r \* $r \)`
n=`expr $n / 10`
done
if [ $a -eq $s ]
then
echo "Armstrong Number"
else
echo -n "Not an Armstrong number"
fi

Output
[vijai@localhost loops]$ sh armstrong.sh
Enter a number : 370
Armstrong Number