BASH let command..gives wrong result on padded numbers -

the following code prints 4 expected:

let x=21 let x=$x-1 echo $x

but following prints 16:

let x=000021 let x=$x-1 echo $x

could explain difference?

00021 octal constant. output 16 correct decimal result. octal value use

printf "%o\n" $x

remove leading zeros if number decimal.

Scrio