Bash 12 - 08 Value too great for base (error token "08")

So, I'm trying to calculate 12-08 (not 12-8) and get the following error:

let: 08: value too great for base (error token is "08")

Here's the sample code:

first=12
second=08
if [[ ($first > $second) ]]; then
    let fin=first-second
else
    let fin=second-first
fi

P.S Sorry about the spacings

If you precede a number by 0, bash treats the number as octal. As octal is base 8 with digits ranging from 0 to 7, 08 is out of range for octal.

Now you have two options to do decimal calculation:

• Omit preceding 0:

  $ echo $(( 12 - 8 )) 
  4
  

• Explicitly mention base as decimal by 10#:

  $ echo $(( 12 - 10#08 )) 
  4