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In this tutorial, you’ll learn **what is a perfect number **and also create **Shell Script**** **to check a number is perfect number or not.

## What is a perfect number?

A number whose **sum of factors** (excluding the number itself) is equal to the number is called a **perfect** **number**. In other words, if the sum of positive divisors (excluding the number itself) of a number equals the number itself is called a **perfect number**.

**For example**: 6 is Perfect Number since divisor of 6 are 1, 2 and 3. Sum of its divisor is

1 + 2+ 3 =6

and 28 is also a Perfect Number

since 1+ 2 + 4 + 7 + 14= 28

Other perfect numbers: 496, 8128

## Shell Script to check a number is perfect number or not

```
#!/bin/bash
read -p "Enter a number " num
sum=0
for ((i=1;i<num;i++))
do
if((num%i==0))
then
((sum=sum+i))
fi
done
if((sum==num))
then
echo "$num is a perfect number"
else
echo "$num is not a perfect number"
fi
```

**Output**

anupmaurya@linux:~$ ./perfectnumber.sh Enter a number 28 28 is a perfect number anupmaurya@linux:~$

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