Container Checksum

Container Number

Say What?
Shipping containers have a unique ID or code or, err, number. Admittedly it's not a number per se as there are letters too. There are 11 digits in this ID/code/number of which 10 are the actual ID and the final number (this is an actual number) is a checksum.

A checksum is a mathematical thing. If you type in the 10 digits of the code and you've made a mistake, ie you hit the "S" key instead of the "W" key, then as long as you typed the checksum digit (the last digit) correctly the maths won't work out and (if the system is programmed thus) you should get an error.

So - type in the ID SUDU5463476 and click "Check Number". This should return "CORRECT...". Now change any of the digits to see what happens. BUT!!! this is not 100% failsafe. Sometimes the maths does actually work out that a WRONG digit can still result in the same checksum. Think of it as more of a "Catches *most* errors" rather than 100% definite.
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