At least on the numpad it makes sense. One of the most used buttons in accouting (the 0) is assigned to your thumb and it can rest on the oversized button. As

At least on the numpad it makes sense. One of the most used buttons in accouting (the 0) is assigned to your thumb and it can rest on the oversized button. As for the number row, this seems to sum things up nicely: http://ux.stackexchange.com/questions/39544/keyboard-number-row-ordering http://ux.stackexchange.com/questions/39544/keyboard-number-... Basically the 0 was added near the O because pre-zero being included typists used the capital O as zero. Thus zero was placed near O as a matter of usage.