Rule of three
The rule of three is thc name of a calculating
operation, which may look as followsr
:]5 875 x435
Exam?le:
-'r;
:
I
First
you
sct up the largest factor of the
dividend
(above
the line)
preceded
by a 0, thus 035875.
The
nought is introduccd
to
keep
you
frorn exceed-
ing the capacity of the machine. Prcss thc tabu-
l-",
lEl.
lr will be seen rhar_rhc
posirion
indi-
c-rtor
is now
rct
ro
thc
c\trcmc
Jcft in thc
multipli.r
rcgistcr,
and
consequently
you
carry out
the
mul-
tiplication by the figures 435 in thc order
thcy
appear,
lrom
lelt to rigbt in tbe multiplier. You
therefore
multiply first by 4. Then
press
the rigl,t-
i",i'li! \"r
@!
;nd multirlr by r.
Prcrs right-
hand
shifc
Lcy
-on.c
more and mu)tiply b1 5. Thc
multiplier
registcr
shows
To the
left in
thc
product
registcr,
you
now
get
,
.
which is
your ploduct.
The multiplier register rc
cords the
answer
Clear
setting and
multiplier registers. Set up 725.
As the first figure of the divisor is
grcater
than
the first figurc of the dividend one nought is set
up
in
fronr
ol: tLc
divi.or. Tlris nill
girc
one nrore
dccin,al in thc
answer.
The nought in
front of
the
number is not necessary.
il:';"'i:Jil*:;:'
(sl
and carr)' out the division
If thc division is uneven, there will be a remainder
which is less
than
the divisor and it will be shown
in thc
product
register'.
19
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