



 
Carol, The error is called a TRANSPOSITION ERROR. But such errors are not confined to children  we all make them. That is why identification numbers like those found on your driver's license and passport, on barcodes, and many other places, contain a check digit which detects a transposition error made when copying the number. You can learn more about these notions from Wikipedia  look up "transposition error" and "check digit." Chris  


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