numbers

Something has been bothering me lately. Why is it that the numbers on the phone and the numbers on a calculator are opposite? I just don't understand.

I went to the grocery store the other night to get some stuff. Before I quit working at the grocery store I hated going to the self check line for a few reasons. 1-I stood behind a check stand at work I wasn't about to check out my own groceries and not get paid. 2- I felt like if I did it myself I was taking away someones job. 3-It really frustrated me that I couldn't clear it myself and I would end up standing there waiting for the clerk to clear the system when I knew how to. Since, I no longer work at a grocery store My feelings have changed. I usually head to the self check out line for a few reasons. 1-I know not to remove any bags until I am done paying. 2- I know that it won't let you scan the next item until the one you just scanned is in the bag 3- I know all the produce codes and I like seeing people look on in amazement as I type the codes without looking. (silly, I know) The thing I don't like is when the machines put the numbers in the phone order. It really messes me up. Look at any check stand/till the numbers are like they are on a calculator not a phone. So, the other night I was having trouble. I know the code for jalapenos. It is my favorite code why isn't it working. That is when I realized that the numbers weren't in the right order. Then of course I was thinking way to hard about what the code because normally I just throw the produce on the scale and type without thinking but suddenly I couldn't remember my favorite produce code. It is 4693 and I kept typing 4639.

Which brings me back to my original question why are the numbers on the phone opposite from the ones on the calculator?