Here’s the reason why Calculators and Phones have opposite keypad

I bet you never would have noticed that Calculators and Phones have buttons on the opposite ends. With the coming of smart phones we carry both of these in our pockets, but still all these years , we have failed to notice the basic difference in their keypad.

Did you ever notice such a difference and question?

Well, no. But, it’s kind of strange. Both of them have nine digits piled up in sets of three, but the only digit common to be in place is 5.

It’s not like that on just the old technology.

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Old Keypad

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Even the latest technology repeats the same mistake.

Iphone Keypad
Source: Grasshopper
Iphone Calculator














But the Question is: Is it really a big mistake and no one has given a thought to it?

Round Dial
Round Dial Telephone

When the phones switched over from round dials, they didn’t just adopt the standardized keypad of the calculators. Rather they flipped the keypad upside down.


When the adding machines were first developed, Sundstand was the first company to introduce this modern calculator keypad in the 1950s which is still used till date.


Before this Bell Labs did an exhaustive research in developing keypads. They looked at all possible layouts and tried out many different variations to select the one which looks natural and easiest to operate.

When they came up with these, they definitely didn’t know about its future use in the smart phones.



The engineers at the Bell Laboratories found that having 1-2-3 at the top row was easiest to use.

Another reason is that the earliest phones had round dials. These dials had 1 on the top right and 0 on the bottom. In order to keep the positions standardized they were to place 1 on top right and 0 on bottom on new keypads. But, that would be unnatural as the people have the habit of reading left to right. As a result 1 was placed on the top left followed by 2 and 3.

When it comes to phone, this kind of keypad has an added use that calculator doesn’t. Texting. It makes sense now, reading alphabets top to bottom looks natural and easier to interpret.

But this would make you wonder why calculators don’t start with 1-2-3 on the top row.

Rumor is that even the Bell Engineers wondered that why was this change not brought if it was more effective. One theory suggest that the earlier cash-register operators and data entry operators, who used calculators regularly had already become adept to keypads with 1-2-3 at the bottom that changing it would reduce their speed.

There is no conclusive evidence but the theory does make sense.


Saksham Dewan

Saksham Dewan is a blogger from India, a quizzer, a chess player, and a finance enthusiast. He is a student at Shaheed Sukhdev College of Business Studies majoring in Finance. He loves to write on topics he startled by, be it be anything. To fulfill his quizzing dreams he also runs a Business Quizzing Blog, not only to pursue his interests but also help others preparing for such quizzes.