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  • @Rahul Gotta love a Matrix reference! +1 – Sylas Seabrook Jan 24 '14 at 4:48
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    @JoeMcGrath I'm only asking because it sounds like the question of someone who's never used a stationary phone, but grew around mobile or at least wireless phones. The fingers were heavily used on stationary phones (and actually the thumb - not so much). – Vitaly Mijiritsky Aug 21 '15 at 15:31




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    @musiphil: best argument ever heard – Bernhard Dec 14 '16 at 10:33




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enter image description here Benford's law (wikipedia)

Phone numbers


  • I am sorry but could not understand the connection between the question and your answer. What about the zero btw? – Abektes May 27 '14 at 14:38

In the early sixties I took a year out of university and got a job in the internal audit department at the head office of a large insurance company in Toronto.

A substantial part of my job involved using an electromechanical calculator to check figures submitted by various departments. The keyboard layout was identical to present computer layouts as well present digital calculators. Index finger was for the left column, next two for adjacent ones. Thumb did zeros exclusively. I became very fast at this touch based skill, as my eyes were on the numbers on paper (there was no visual feedback - just the numbers that were printing on the tape, but you didn't look at that. Mistakes were extremely rare, and required a redo of the entire document. This was also in the days of rotary phones.

Imagine my shock when reversed digital keys appeared on telephones. My skill was not transferable to them. The decision by Bell Labs, or whomever, to reverse the layout was thoughtless at best, stupid at worst.


The phone design of 123 Top, and 789 Bottom was merely based on the research done by the Bell's labs:


So with no (or not enough) factual studies to rationale the designs, we can say that:


Push-button or Touch-tone keypad designs are merely based on the Bell's labs research, and I would add it is a logical order when no studies proving the opposite existed at that time. Reading is Top to Bottom, Left to Right for those who designed it (in USA), so it starts 1,2,3 Top...to 7,8,9 Bottom [Total of 9 digits] we have three rows with three digits in each.

Zero [a unique digit]:

Zero is the digit number 10 (does not fit in a 3x3 matrix), it has to be located somewhere. Create another row (of 3 digits) below as you going Top to Bottom. Now if you put it on the left or right corner, you need a reason to do so. Locating it in the middle makes it a unique location (it is a unique digit) and easy to spot [my personal point of view].

Another point: if you take a look at the Rotary-dial phones, notice that they mostly have the Zero as the first digit located bottom middle, so Push-button design kept the zero in the same location as the Rotary-dial design, maybe?

*Some Rotary-dial phones has the zero a little to the right.

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*They added the [ *,#] later on (added more functions and fill out the 4th row).

Mobile phones just matched early phones' design.


As answered above regarding Benford's law:

"Briefly explained, Benford's Law maintains that the numeral 1 will be the leading digit in a genuine data set of numbers 30.1% of the time; the numeral 2 will be the leading digit 17.6% of the time; and each subsequent numeral, 3 through 9, will be the leading digit with decreasing frequency."

Numpad on keyboards were not designed with the goal to make phone calls, they were rather designed for accounting and calculations purposes (helpful in applications were numbers are heavily used). Adopting the Benford's law, it makes more sense to locate the most used numbers close to the human fingers on a keyboard (1,2,3 Bottom...7,8,9 Top).

Notice that Zero is always placed bottom no matter the numbers layout. Users just got used to it there? maybe.

Personally, I saw many bank employees or generally accountants using the numpad on keyboards very fast without the need to look at the keyboard, maybe they are just used to it. What if the design is Top - Bottom will they be as fast? Well, not according to Benford's law.

EDIT: Just adding this info from Wikipedia Rotary dial


For this reason, the numbers on the dial are shifted in different countries, or even in different areas of one country, to work with their system because of the difference of the number arrangement on the dial. The dial numbering can occur in four different formats, with 0 adjacent either to the 1 or the 9, and the numbers running in ascending or descending order, with either the 0, 1 or 9 being closest to the finger stop.

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    Personally, I always thought the 0 at the bottom was related to the original way of using phones, were in many cases you had to dial 0 in order to get a communication, while first phone numbers were chronological so Benford's law applied. Then it evolved from there with the * and # added at the sides of 0 number. As for calculators, it just seems logical: 0, dot, 1,2,3.... . Just a theory on a possible explanation, not that it holds a lot of merit or that I have any documentation to support it. Your answer kind of supports this theory, at least in part – Devin Mar 19 '18 at 19:08
  • Good point. So Zero has been always a unique number with unique functionality. Phone systems especially inside organizations till now use Zero for special functions. Push Zero for the operator, Zero to speak to representative...etc. I just wonder why the Rotary-dial although had Zero at the bottom, it is not followed by 1,2,3...but 9,8,7.... Or If we look at it differently they started with 1,2,3... top (from the Right not left tho) and ended with Zero. – Mo'ath Mar 20 '18 at 13:40
  • @Mo'ath - actually, if you understand the mechanics of the early direct-dial phone system (pre-touch-tone, and rotary dials rather than buttons), 0 at the bottom makes sense - on rotary-dial phones, 0 was after 9 because it generated ten pulses on the line for dialling - so it's not really a zero, it's a ten, even in these touch-tone days. – Jeff Zeitlin Mar 20 at 18:22
  • I added it to my answer above. A quick search produced this: "Different pulse systems are used, varying from country to country. For example, Sweden uses one pulse to signal the number zero, and 10 pulses to signal the number nine. New Zealand uses ten pulses minus the number desired; so dialing 7 produces three pulses. In Norway, the North American system with the number '1' corresponding to one pulse was used, except for the capital, Oslo, which used the same "inverse" system as in New Zealand" – Mo'ath Mar 20 at 19:29


  • Does this fundamentally affect the layout choice though? In both situations, I need to use all of the keys available, and experience no bias toward higher or lower numbers. – doppelgreener Jan 20 '14 at 6:58

protected by Community Dec 9 '15 at 8:09


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