TM 5-6640-212-14
ferent numbers. In the previous example, 12 was
NOTE
multiplied by 12. Suppose it was necessary to multiply
In division problems, the left-hand
12 by 31, and 12 by 15. After completing the first
figure of the divisor on the keyboard
multiplication, the machine reads as follows: upper dials,
must always be either directly under
12; keyboard, 12; lower dials, 144. To multiply 12 by 31
the left-hand figure of the dividend in
and by 15.
the lower dials, or beyond it to the
(1) Clear nothing on the machine because clearing
left.
is not required. Leave the 12 on the keyboard.
(4) Turn the operating crank backward until the bell
(2) Change the upper dials to the next multiplier, 31
rings. Turn the crank forward one turn. (The red 1 in the
in this example. Change the I in the upper dials to 3 with
upper dials is the first digit of the answer). Shift the
two forward turns of the operating crank. Shift carriage
carriage one place to the left. Turn the crank backward
one place to the right. Change 2 in the upper dials to 1
until the bell rings. Turn the crank forward one turn (bell
with one backward turn of operating crank.
also rings on the one forward turn to warn you not to go
(3) The result should be:
any farther).
Upper dials
31
(5) Continue this operation of shifting the carriage
Lower dials
372
one place to the left, turning the crank back until the bell
Answer
rings and turning the crank forward one turn.
In a similar manner, change the upper dials to 15 and the
(6) The results should be:
result should be:
Lower dials
0 (remainder)
Upper dials
15
Upper dials
144 (answer)
Keyboard 12 Lower dials 180
(7) If the crank is turned backward rapidly and goes
Answer
a turn or two past the bell, simply turn the crank forward
(4) It can be seen from the above that multiplication
until the bell rings, and stop. Listening for these bells
can be done in either direction. As long as the figures on
makes it possible to perform the division without
the keyboard and in the upper dials are correct, the result
watching the machine.
in the lower dials will be correct.
h. Using Decimals. On all calculating machines,
g. Dividing Whole Numbers. As multiplication is a
fractions are expressed as decimals. For example, 1/4 =
process of repeated additions, accomplished by forward
.25, 5/8 = .625, etc. The arrangement of the dials and
turns of the operating crank, so division is a process of
the keyboard makes it particularly adaptable to handling
continued subtractions, accomplished by backward turns
calculations involving decimal numbers. All decimals
of the operating crank. The repeat key must be
can be set for a complete group of problems before
depressed when doing division. For example, to divide
starting the work, and all the calculations can be
1728 by 12:
completed without any resetting of the decimals. The
work is done entirely around preset, fixed decimals. The
(1) Depress the repeat key. Clear the machine.
one simple rule for setting decimals is as follows:
Keyboard decimal + upper dial decimal = lower dial
(2) With the carriage in position 1, set the dividend,
decimal.
1728, on the extreme right of the keyboard.
(1) Keyboard decimal markers. The keyboard
Make one forward turn of the operating crank. Depress
decimal is marked by turning one of the small knurled
the keyboard clear key and turn clear-out crank
wheels below the keyboard to the right so that the yellow
clockwise. (This clears the keyboard and clears the 1
decimal marker appears between the proper keyboard
out of the upper dials).
columns.
(3) Set the divisor, 12, on the right of keyboard and
move the carriage two spaces to the right so that the
decimals are marked by the gray pointers which can be
divisor, 12, is in direct alinement with 17, the first two
easily positioned to point off the decimal exactly as with
figures of the dividend in the lower dials.
paper and pencil. To set a decimal at two in the dials,
simply set the marker to the left of the two on the slide
.
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