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I stumbled across this pdf about Magnetic Ink Character Recognition, and found it enjoyable if a bit dry at the end. The impact of the distinct numerals has had on graphic design and type over the last 50 years to be fascinating. I thought, "I bet there is someone else on 'phile that would find this neato."
The article includes a bit on the source of typeface E-13B's fittingly industrial name, and the forces that called for the design of MICR Numbers for checks.