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Calculators today are so ubiquitous that you probably don’t give them a second thought. It’s unlikely you are ever without one so long as you have your smart phone, tablet, laptop, desktop, etc. at hand. You can buy battery operated calculators for a dollar at any number of stores and you will never even question their accuracy. But it wasn’t always that way.
Calculating machines really started becoming practical business tools in the late 19th century. However, only large banks, insurance companies, government agencies, etc. could afford them in the beginning. But it wasn’t just accountants and bookkeepers in large organizations that had a use for these kinds of machines. If you think about it, there are a large number of professions who use math as part of their job. There would be, of course, merchants and salespeople, but also various tradesmen such as carpenters and plumbers.

newspaper ad from 1925
And thus we come to the Baby Calculator. The Baby Calculator was marketed towards the home user for bills and shopping. It was also marketed to folks who worked with numbers but for whom a full-size adding machine was impractical. It seemed to be especially popular with individuals “who worked outside”. It was also marketed towards small businesses and bookkeepers who needed a less expensive alternative to the larger adding/calculating machines then available.

magazine ad from 1925
The Baby Calculator was a troncet-type adding machine made entirely of pressed steel. When you purchased this item it would have included a leatherette case, instructions, some advertising material, and an aluminum stylus. There were three versions sold throughout its history. For versions 1 and 2 the differences were cosmetic as each was the same size and made from the same materials. These measured 2.9375″ W x 5.75″ L x .4375″ H and weighed about 5 ounces. Version 3, however, was made from pressed steel with a plastic back plate. It weighed 6 ounces and measured 3.25″ W x 5.75″ x .3125″ H. It also had a 9 digit display as opposed to a 7 digit display for versions 1 and 2.
The different versions were sold during the following time periods:
- Version 1 – 1923 – September 1945
- Version 2 – October 1945 – October 1947
- Version 3 – November 1947 – until at least 1951
As I’ve mentioned in the past it should be understood that there would be overlap during when the different versions were sold. While version 3 was available by November 1947 version 2 was still being sold also until stock ran out.

version 2

version 3
If you look at version 1 you can see at the top of the front it states “Patent Applied For”. There never was a patent granted for this machine. In my opinion this was a marketing ploy meant to give the impression that this was better than its competition.
While there were other troncet-type adders on the market during the time the Baby was sold, its main competition seemed to be the higher-quality Ve-Po-Ad (Vest Pocket Adder) Calculator. There are a number of Baby Calculator ads stating that this is a less-expensive vest pocket adding machine. The Ve-Po-Ad seemed to be a better seller and was offered by many office suppliers while the Baby Calculator was relegated mostly to mail order, traveling salesmen, and some retail outlets.
Consumers’ Research, Inc., the precursor organization to the Consumers Union which split from them during a labor dispute, for many decades issued a monthly bulletin where they tested various consumer goods. In October 1949 they published an article titled “Small or Pocket Adding Machines” where they tested three different adding machines; the Addometer, the Tasco Arithmometer, and the Baby Calculator. The Baby Calculator received a rating of “Not Recommended”, their lowest grade. Following is their recommendation overview, but in the “Other Information” section below you can download the entire article.

Oct 1949 Consumers’ Research Bulletin Recommendation. The Tasco Arithmometer received an even worse review.

newspaper ad from September 1945

magazine ad from October 1945
The company responsible for making and selling the Baby underwent a number of name changes in its history, although all of them were similar.
- Baby Calculator Co – 1923
- Baby Calculator Sales Co – 1925-1929
- Baby Calculator Machine Co – 1924-1925, 1930-1932
- Calculator Machine Co – (beginning in 1933 according to a trusted, but unsubstantiated, source) but proven from 1945-1950 and likely until it stopped being manufactured

newspaper ad from 1951
According to USPTO trademark 247,450 Harold S. Zewiske was doing business as the Baby Calculator Sales Company. Mr. Zewiske died tragically in a plane crash in 1959 and while listed as being an editor for Vogue there was no mention of his connection with the Calculator Machine Company. This tells me that either Mr. Zewiske was simply no longer engaged with that company or that it was out of business by 1959. And it could be both. However, with the latest ad that I can find being in 1951 it is my opinion that the Baby Calculator wouldn’t have been around for much longer than that.

Harold S. Zewiske
Other Information:
- v2 Baby Calculator Instructions
- v1 Baby Calculator Brochure
- v1 Baby Calculator Brochure You Need This
- Consumers’ Research Bulletin October 1949 “Small or Pocket Adding Machines”
Notes:
- The Baby Calculator Co (1923, July). Wanted-Male Help. Chicago Tribune, page 25
- Baby Calculator Sales Co (1925, February). advertisement. Popular Mechanics, page 174
- The Fair (1925, December). advertisement. Chicago Tribune, page 5
- Baby Calculator Machine Co (1930, June). advertisement. Popular Mechanics, page 139
- Storey-Kenworthy Co (1945, September). advertisement. Des-Moines Sunday Register, page 12-X
- Calculator Machine Co (1945, October), advertisement. The Pittsburgh Courier, page 3
- Calculator Machine Co (1947, November). advertisement. Popular Mechanics, page 340
- Editors (1949, October). Small or Pocket Adding Machines. Consumers’ Research Bulletin, pages 11-12
- Cox & Rich Stationers (1951, May). advertisement. San Mateo Times, page 7
- Editors (1959, February). Plane Crash Brings Grief to Many Here. Chicago Tribune, page 3
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Hmmn, Calculator week in the Typosphere – Joe Van Cleave is hot on them now too (:
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Neat to read the background on this on, thanks. Had so far really only seen the Ve-Po-Ad of the US models. Over here in Europe there’s of course lots of Addiators of various vintage and some Produx. Adding works well, using them for multiplication and division is a bit of a challenge 🙂
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Oh no, there were many of these types of “calculators” offered in the US during this time besides the Baby and the Ve-Po-Ad. Without trying too hard I can think of the Tom Thumb, Tasco Arithmometer, Midget, and Magic Brain (made in Japan). There was also a number of Japanese made generic, unbranded calculators available at discount stores. And there were a number of European made calculators available in the US such as the Arithma and Kalkometer.
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I have one that works exactly the same as yours. I am at a loss as to how one does division or multiplication on one.
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The instructions will show you how, but the honest truth is that these were made for simple addition and subtraction. I could never get the hang of division on one of these things but once you can wrap your mind around how the multiplication works it’s actually quite clever.
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Mine did not come with any instructions. I figured you just added over and over.
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All of these addiators work the same so the instructions available at the end of the post will show you how you can do multiplication and division.
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I just got one of these Baby Calculators as a Christmas gift from my father-in-law. He said it used to belong to his father. I think he gave it to me more or less as a curious prank. I would like to master it, but the instructions are not very clear.
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I actually just did master the addition. I was overthinking it the whole time.
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