Created SC2080 (markdown)

SC2080.md

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+## Numbers with leading 0 are considered octal.
+
+### Problematic code:
+
+```sh
+echo $(( 16 - 08 ))
+```
+
+### Correct code:
+
+```sh
+echo $(( 16 - 8 ))
+```
+### Rationale:
+
+ShellCheck found an integer literal with a leading zero, but containing the digits 8 or 9.
+
+This is invalid, as the integer will be interpreted as an octal value (e.g. 0777 == 0x1FF == 511).
+
+To have the value parsed in base 10, either remove the leading zeros as in the example, or specify the radix explicitly:
+
+    echo $((10#08)) 
+
+### Exceptions:
+
+None
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!