The 7th digit is a checksum digit, as previously noted. So only 6 "free" digits so a million is correct. You can read more about the container numbering standa

The 7th digit is a checksum digit, as previously noted. So only 6 "free" digits so a million is correct. You can read more about the container numbering standard here: https://en.wikipedia.org/wiki/ISO_6346 https://en.wikipedia.org/wiki/ISO_6346