Why there is a dot(.) on 5 keyof every cellphone?

Have you ever noticed while
typing on your cellphone,
having small dot on number 5
key if not check it now.There
is also small raised bar on the
“F” and “J” keys of keyboards. The reason behind on putting
dot on keypads are pretty
simple,In the early days, items
with numeric pads, such as
caculators and adding
machines were used almost exclusively by accountants and
the like. Since they had to
perform a lot of caculations
fast, most learned a method of
using the keypad without
looking at it. The dot was added as a reference point, so
you could identify the 5 key by
touch.
It’s given so you can locate
where your finger is on the
keypad without having to look…Mobiles have the dot on
the number 5 key on the
keypad, and computer
keyboards have them on the
the F and J keys.
5 is in the middle – and this is a way for you to type and not
look at the numbers – move
your finger to the 5 and you
know where all the other keys
are.