Calculator keypads vs. phone buttons---WHY?

Just occurred to me to wonder: why are the number buttons on calculators arranged 1-3, 4-6, 7-9 starting at the bottom, whereas the ones on touch-tone phones start at the top??
I’ve never noticed any difficulty switching from one to the other, as when calling my accounting department to harass them with my foolish budgeting questions…why is that? Wouldn’t you think we’d be habituated to deal with them one way and have trouble with the other???

It’s not just calculators. Numeric key-pads on computer keyboards, too. I wish they were arranged the same way – either way, just pick one. I don’t really have trouble switching back and forth except when I have to enter my phone number on a key-pad, then I get confused.

Calculators are throwbacks to the old NCR cash registers, with rows of buttons and 0 and 00 at the bottom for quick 10 cent and $1.00 sales.

Then Burroughs calculators copied the style for the first popular calculator machine.

Bell didn’t think much of it and did lots of tests in the late 50’s before bringing out the number pad we have today.

They added # as the “end of a number” and * as “start of a function”, from the previous Teletype, for use with business applications, like credit card input.

I work at a computer, making calls to hospitals to check on patients for an insurance company.

It took me about an hour, at 20 dials and 20 database look-ups per hour, to be proficient touch-typing (no peeking) with both.

I never confuse the two. Not sure why, but then I’m not mixed up by the computer number pad and top-row digits.
I will use those interchangeably without error as well.

I once had an office phone with a built in calculator. I found it impossible to get used to. I have no problem switching from phone to regular calculator/keyboard though.

Without any real stats to corraborate –

According to my dad, who worked for AT&T from 1956-1986, they set up the phone keypad the way it is based on tests given to operators. They had them dial numbers on the keypad the way it is, the way it is on a calculator, and a couple of other variations, and the 1-3 4-6 7-9 *-# version came up with the fastest times, and the easiest to dial without looking.

So you can make lot of wrong number long distance
phone calls when you use the phone like a

Also, so you can learn to push the phone buttons
with your non-dominant (left for me) hand while
using the computer with your right.