It may have been typed in the 1970s.

When I was growing up, my family used my mom's college typewriter, which did not have numeral 1 or 0 keys. Instead, you typed a lowercase L and an uppercase O. It was one of the typing habits, and you didn't even think about it.

When she took a computer programming class, around 1979, the terminals had all of the numerals, and of course she was constantly mixing them up, causing errors. A year later she became the teacher of that class, and completed the requirements for a CS major by staying a semester ahead of her students for a few years. She always reminded her students: "Computers are stupid. They will do exactly what you tell them."

The typewriter that I got for college had all of the numbers. Of course I used it for about a year before ditching it for a word processor. But everybody kept an old typewriter around for many years after that, because you might need one for filling out a form.