<s>
A	O
keypad	B-Device
is	O
a	O
block	O
or	O
pad	O
of	O
buttons	O
set	O
with	O
an	O
arrangement	O
of	O
digits	O
,	O
symbols	O
,	O
or	O
alphabetical	O
letters	O
.	O
</s>
<s>
Pads	O
mostly	O
containing	O
numbers	O
and	O
used	O
with	O
computers	O
are	O
numeric	B-Device
keypads	I-Device
.	O
</s>
<s>
Keypads	B-Device
are	O
found	O
on	O
devices	O
which	O
require	O
mainly	O
numeric	O
input	O
such	O
as	O
calculators	B-Application
,	O
television	O
remotes	O
,	O
push-button	O
telephones	O
,	O
vending	O
machines	O
,	O
ATMs	O
,	O
point	O
of	O
sale	O
terminals	O
,	O
combination	O
locks	O
,	O
safes	O
,	O
and	O
digital	O
door	O
locks	O
.	O
</s>
<s>
A	O
computer	B-Device
keyboard	I-Device
usually	O
has	O
a	O
small	O
numeric	B-Device
keypad	I-Device
on	O
the	O
side	O
,	O
in	O
addition	O
to	O
the	O
other	O
number	O
keys	O
on	O
the	O
top	O
,	O
but	O
with	O
a	O
calculator-style	O
arrangement	O
of	O
buttons	O
that	O
allow	O
more	O
efficient	O
entry	O
of	O
numerical	O
data	O
.	O
</s>
<s>
This	O
number	B-Device
pad	I-Device
(	O
commonly	O
abbreviated	O
to	O
numpad	B-Device
)	O
is	O
usually	O
positioned	O
on	O
the	O
right	O
side	O
of	O
the	O
keyboard	B-Device
because	O
most	O
people	O
are	O
right-handed	O
.	O
</s>
<s>
Many	O
laptop	B-Device
computers	I-Device
have	O
special	O
function	O
keys	O
that	O
turn	O
part	O
of	O
the	O
alphabetical	O
keyboard	B-Device
into	O
a	O
numerical	B-Device
keypad	I-Device
as	O
there	O
is	O
insufficient	O
space	O
to	O
allow	O
a	O
separate	O
keypad	B-Device
to	O
be	O
built	O
into	O
the	O
laptop	B-Device
's	O
chassis	O
.	O
</s>
<s>
Separate	O
external	O
plug-in	O
keypads	B-Device
can	O
be	O
purchased	O
.	O
</s>
<s>
Keypads	B-Device
for	O
the	O
entry	O
of	O
PINs	O
and	O
for	O
product	O
selection	O
appear	O
on	O
many	O
devices	O
including	O
ATMs	O
,	O
vending	O
machines	O
,	O
point	O
of	O
sale	O
payment	O
devices	O
,	O
time	O
clocks	O
,	O
combination	O
locks	O
and	O
digital	O
door	O
locks	O
.	O
</s>
<s>
In	O
1984	O
,	O
the	O
first	O
projected	O
capacitance	O
keypad	B-Device
was	O
used	O
to	O
sense	O
through	O
the	O
shop	O
window	O
of	O
a	O
travel	O
agency	O
.	O
</s>
<s>
The	O
first	O
key-activated	O
mechanical	O
calculators	B-Application
and	O
many	O
cash	O
registers	O
used	O
"	O
parallel	O
"	O
keys	O
with	O
one	O
column	O
of	O
0	O
to	O
9	O
for	O
each	O
position	O
the	O
machine	O
could	O
use	O
.	O
</s>
<s>
A	O
smaller	O
,	O
10-key	B-Device
input	O
first	O
started	O
on	O
the	O
Standard	O
Adding	O
Machine	O
in	O
1901	O
.	O
</s>
<s>
The	O
calculator	B-Application
had	O
the	O
digit	O
keys	O
arranged	O
in	O
one	O
row	O
,	O
with	O
zero	O
on	O
the	O
left	O
,	O
and	O
9	O
on	O
the	O
right	O
.	O
</s>
<s>
There	O
is	O
no	O
standard	O
for	O
the	O
layout	O
of	O
the	O
four	O
arithmetic	O
operations	O
,	O
the	O
decimal	O
point	O
,	O
equal	O
sign	O
or	O
other	O
more	O
advanced	O
mathematical	O
functions	O
on	O
the	O
keypad	B-Device
of	O
a	O
calculator	B-Application
.	O
</s>
<s>
The	O
invention	O
of	O
the	O
push-button	O
telephone	O
keypad	B-Device
is	O
attributed	O
to	O
John	O
E	O
.	O
Karlin	O
,	O
an	O
industrial	O
psychologist	O
at	O
Bell	O
Labs	O
in	O
Murray	O
Hill	O
,	O
NJ	O
.	O
</s>
<s>
On	O
a	O
telephone	O
keypad	B-Device
,	O
the	O
numbers	O
1	O
through	O
9	O
are	O
arranged	O
from	O
left	O
to	O
right	O
,	O
top	O
to	O
bottom	O
with	O
0	O
in	O
a	O
row	O
below	O
789	O
and	O
in	O
the	O
center	O
.	O
</s>
<s>
Telephone	O
keypads	B-Device
also	O
have	O
the	O
special	O
buttons	O
labelled	O
*	O
(	O
star	B-Language
)	O
and	O
#	O
(	O
octothorpe	O
,	O
number	O
sign	O
,	O
"	O
pound	O
"	O
,	O
"	O
hex	O
"	O
or	O
"	O
hash	O
"	O
)	O
on	O
either	O
side	O
of	O
the	O
zero	O
key	O
.	O
</s>
<s>
Although	O
calculator	B-Application
keypads	B-Device
pre-date	O
telephone	O
keypads	B-Device
by	O
nearly	O
thirty	O
years	O
,	O
the	O
top-to-bottom	O
order	O
for	O
telephones	O
was	O
the	O
result	O
of	O
research	O
studies	O
conducted	O
by	O
a	O
Bell	O
Labs	O
Human	O
Factors	O
group	O
led	O
by	O
John	O
Karlin	O
.	O
</s>
<s>
This	O
study	O
concluded	O
that	O
the	O
adopted	O
layout	O
was	O
best	O
,	O
and	O
that	O
the	O
calculator	B-Application
layout	O
was	O
about	O
3%	O
slower	O
than	O
the	O
adopted	O
telephone	O
keypad	B-Device
.	O
</s>
<s>
Despite	O
the	O
conclusions	O
obtained	O
in	O
the	O
study	O
,	O
there	O
are	O
several	O
popular	O
theories	O
and	O
folk	O
histories	O
explaining	O
the	O
inverse	O
order	O
of	O
telephone	O
and	O
calculator	B-Application
keypads	B-Device
.	O
</s>
<s>
Another	O
explanation	O
proposed	O
is	O
that	O
at	O
the	O
time	O
of	O
the	O
introduction	O
of	O
the	O
telephone	O
keypad	B-Device
,	O
telephone	O
numbers	O
in	O
the	O
U.S.	O
were	O
commonly	O
given	O
out	O
using	O
alphabetical	O
characters	O
for	O
the	O
first	O
two	O
digits	O
.	O
</s>
