Key Points About Add-A-Mite

  • The design of Add-A-Mite is very similar to Webb Adder.
  • This calculator is made from Aluminum, Iron, and Brass.
  • This pocket calculator was manufactured by the company, Monogram of California

Add-a-Mite History

Far back in the past, written numbers used to be inexistent, with humans using only fingers and toes to count. However, this improvisation was evidently limiting and grossly inefficient, resulting in the Abacus’s invention.

Abacus, to date, is famously regarded as the first-ever calculating tool invented by man. While still in use to date, the calculation technology has drastically evolved over the years, with multiple calculating devices introduced for commercial use. One such calculating device is the Add-A-Mite pocket calculator.

Quick Facts

The early 1950s 
Monogram of California
Original Use
Originally used to add and subtract US dollars and cents.

Manufactured and made commercially available in the early 1950s, the Add-A-Mite mechanical pocket calculator is made of iron, aluminum, and brass and was initially used for adding and subtracting US dollars and cents. Add-A-Mite pocket adder was manufactured by Monogram of California in San Francisco.

Featuring an elegant and reminiscent design, very similar to the Webb Adder used to self-check when shopping. However, unlike the latter, the Add-A-Mite mechanical pocket calculator uses concentric disks. Apart from being a calculating machine, Add-A-Mite doubles as a pocket toy.

Add-A-Mite Pocket Calculating Device
Add-A-Mite Pocket Calculating Device

Add-a-Mite: How It Worked

This calculating device features a relatively straightforward working principle: the cursor on the right is depressed and dragged to the number you wish to add, 0 to 99. When released, the cursor engages a gear tooth on the back of the disc. Also, if dragged clockwise back to the 0 positions, your number is added to the result.

Crossing from 99 to 00 causes an automatic carry into the hundreds window, allowing sums up to $24,99. Subtraction works similarly by starting from zero and dragging counterclockwise to the desired number.

Add-a-Mite: Historical Significance

Although made by the company, Monogram of California, the construction of the Add-A-Mite pocket calculator was not very successful since the small numbers make it difficult to read, and there is no fixing mechanism, not even at zero, so the setting cent is almost analogous and thus quite prone to error.


Add-A-Mite Explained – Everything You Need To Know FAQs (Frequently Asked Questions) 

What is Add-a-Mite? 

Add-A-Mite is a relatively simple and portable mechanical adder made from iron, brass, and majorly aluminum.

When was Add-a-Mite invented?

The early 1950s

Where was Add-a-Mite invented?

San Francisco

Who invented Add-a-Mite?

Monogram of California

Are Add-a-Mites still used?

No. The invention wasn’t really a success.

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