Trivia 020: Checking Numbers

Although they are not as commonly used today, most of my readers are probably familiar with using bank checks. While it is rare to use them for payments at the grocery store, perhaps you have used them before for big purchases, like paying rent. They are also useful when you need to set up direct deposit for payments. At the bottom of each check are a series of numbers. The first number is your bank’s routing number (which identifies the bank), and the second is your account number (which identifies you). If you consider these numbers, you may have noticed the strange shape of their font:

MICR characters

It’s a very strange font; boxy, with large bulges in weird places. It looks very sci-fi, in my opinion. This font is known as E13B, a name as robotic as the font itself. It is designed to help computers read the printing – but not in the way you might think.

In the early 1940’s, bank checks were processed by hand – tellers would have to sort checks into folders according to their routing numbers. Other methods included punching holes in the checks, allowing tellers to use a metal key to sort the checks. However, both methods were very time consuming and prone to error.

In the 1950s, the Stanford Research Institute and General Electric Computer Laboratory worked to create a system to process checks more quickly and efficiently. The Technical Subcommittee on Mechanization of Check Handling analyzed several solutions, including bar codes, fluorescent ink, and spot codes. Ultimately, they recommended the use of magnetic inks.

Magnetic ink character recognition (MICR) works by using ink mixed with iron oxide. When the check is passed through a reader, a magnetic read head measures the change in the magnetic field produced by the ink. This is similar to how a tape recorder works. The fonts used for this process are specifically designed to produce unique, machine-readable waveforms. The thicker parts of the numbers produce stronger signals than the thinner parts. This enables a computer to understand exactly what is written.

megnetic scanning of E13B font

Most of North America and Asia use the E13B font that many of my readers are familiar with. However, Europe and South America mostly use a different font – CMC7. This font uses spacing between magnetic lines instead of different thicknesses to produce the magnetic symbols. However, this font is slightly more difficult for computers to recognize using optical character recognition (OCR), which is used as a backup if the MICR fails.


CMC7 font

Eventually, as OCR becomes more precise, we may not need magnetic ink anymore. However, it probably will not fully go away, as this technology is currently employed by banks everywhere. When and if the time comes for us to stop using MICR, the numbers on your checks may be written in other fonts, such as OCR-A.

If you know anyone who would like to receive these, please have them send an email to [email protected] And if you don’t want reminders of old ways of payment, let me know and I can take you off the list.


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