need help with creating directories and variables

i'm trying to write a script that has 2 variables, and uses the 1st variable as a number and the 2nd a name to create directories. so if you typed in ./myscript 5 week, it would create 5 directories named week1 - week5. whenever i run this, i get an error message saying week5 already exists, so i have something wrong in the while loop. here is what i have.

if [[ $2 == "" ]]; then
  echo "error, please specify a name"
  exit 0
fi
if [[ $1 -lt 1 ]]; then
  echo "error, number is too small"
  exit 0
fi
if [[ $1 -gt 10 ]]; then
  echo "error, number is too big"
  exit 0
fi
while [[ $1 -lt 11 ]]; do
  let $2=$2-1
  mkdir $2$1
done

seems, you already having a directory called week5

before mkdir you can check the directory is there or not.

 
if [ -d $2$1 ]
then
echo "Directory $2$1 exists"
else
mkdir $2$1
fi

You can also use find command syntax in the beginning of the script to check and remove if it is already exist.

find / -type d -name week5 -exec rm -rf {} \;

the directory week5 only exists after i run the script, so the while loop is wrong. there is no directory week5 until the script runs, and then it comes back with the error, so the script is using the variables right to make the first week5 directory, but it won't make week4, week3, week2, etc... it just says week5 exists. i just want it to make all the other directories, which is where it's giving me error.