#!/bin/bash

echo -n "Enter your number: "
read answer

if [ "$answer" == "6022000000000000000000000" ]
then
echo "You picked the Avogadro Number! $answer"
else
echo "That number isn't the Avogadro Number!"
fi

$ ./av.sh
Enter your number: 3120280138
That number isn't the Avogadro Number!

$ ./av.sh
Enter your number: 6022000000000000000000000
You picked the Avogadro Number! 6022000000000000000000000