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MpNROE CALCULATING MACHINE MODELS Hand Operated LN OPERATING INSTRUCTIONS MONROE CALCULATING MACHINE Hand Operated LN Models © MpNROE MONROE CALCULATING MACHINE COMPANY. INC. Generol Offices, Orange, New Jersey Copyright 1953 Monroe Calculating Machine Company, Inc. Printed in U. S. A. 1045-S September 1958 FOREWORD T HIS BOOKLET describes the operating controls and parts of the Monroe Model LN Calculator and gives step by step instruc¬ tions on the four basic arithmetic functions; addition, subtraction, multiplication and division. The directions apply to both the 8 and 10 bank LN type Monroe hand operated machines. The former model has an eight column key¬ board, eight places in the upper dials, and sixteen places in the lower or result dials. The latter, Model LN 200, is equipped with a ten column keyboard, ten places in the upper dials, and twenty places in the lower dials. The actual operation of these two models is exactly the same; the only difference is in their figuring capacities. CONTENTS Description of Operating Controls and Parts . 9 Addition and Subtraction. 11 Multiplication. 12 Division. 14 Decimals . 16 Addition and Subtraction of Decimal Numbers. 17 Multiplication of Decimal Numbers. 18 Division of Decimal Numbers. 20 &ac>~rS -- S£e Aff'SJ? MONROE CALCULATOR Model LN Operating Controls 1. Upper Dials 2. Lower Dials 3- Carriage Shift Knob 4. Clear-out Crank 5 . Operating Crank 6. Repeat and Non Repeat Keys 7. Keyboard Clear Key 8. Carriage Shift Lever 8 MONROE MODEL LN Description of Operating Controls ond Parts 1) Upper Dials The set of dials located in the upper part of the moveable carriage is called the upper dials. These dials show the quotient (answer) of a division problem in red figures. In multi¬ plication, they show the multiplier (number by which you multiply) in black figures. 2) Lower Dials These are the sixteen (or twenty) dials located in the lower part of the carriage. The lower dials show the answer in addition, subtraction, and multiplication. They show the remainder in division. 3) Carriage Shift Knob This knob, located at the right end of the carriage, is for shifting several places at a time. Simply lift up on the knob and slide the carriage to the desired position. 4) Clear-out Crank This is the smaller crank located at the right end of the carriage. A forward (clockwise) turn clears the upper dials, and a backward (counter-clockwise) turn clears the lower dials. 5) Operating Crank The operating crank is the larger crank located on the right side of the machine. This crank is used in all opera¬ tions on the machine. The operator should clearly understand what is meant by a forward turn and a backward turn of this crank in order to follow the instructions in this booklet. 9 6) Repeat and Non-repeat Keys When the repeat key (key marked "R") is depressed, any figures set on the keyboard remain down until cleared by the operator. W'hen the non-repeat key (key above repeat key) is depressed, the keyboard clears after each turn of the opera¬ ting crank. The repeat key mus/be depressed when performing multi¬ plication and division. 7) Keyboard Clear Key The keyboard keys are cleared in one of two ways, either by depressing the large square zero clear button, which clears the entire keyboard; or by depressing the individual "zero" clear keys at the bottom of each column, which clear keys one at a time. 8) Carriage Shift Lever By a half turn of this lever, located at the left front of the machine, the carriage may be shifted to the right or left as desired. The operating crank must be in upright, or "neutral" position when shifting. TO CLEAR THE MONROE MODEL LN The operator should always remember to clear the entire machine before starting any new work. Complete machine clearance is a simple procedure which can be done almost subconsciously. To clear keyboard — Depress Keyboard Clear Key To clear upper dials - Make a complete forward turn of Clear-out Crank To clear lower dials - Make a complete backward turn of Clear-out Crank NOTE: The operating crank must be in upright, or "neutral" position when clearing. 10 ADDITION AND SUBTRACTION Addition and subtraction can be accomplished with the carriage in any position but it is suggested that the carriage be placed in posi¬ tion "1", that is, as far to the left as possible. The most rapid and efficient way to add and subtract is with the non-repeat key depressed so the numbers automatically clear from the keyboard. TO ADD Depress Non-repeat key. Clear machine. Set on keyboard Set on keyboard Set on keyboard In lower dials 12 Make one 23 Make one 34 Make one 69 Total forward turn of forward turn of forward turn of Operating Crank Operating Crank Operating Crank TO SUBTRACT Non-repeat key depressed. Clear machine. Set on keyboard 45 Make one forward turn of Operating Crank Set on keyboard 15 Make one backward turn of Operating Crank In lower dials 30 Answer Repeat key addition and subtraction Addition and subtraction can be done exactly as above with the repeat key depressed. When this is done, the number added or subtracted remains on the keyboard after the turn of the operating crank. This saves time when adding and subtracting numbers which have one or more digits the same. Try it with the following example: Depress Repeat key. Clear machine. Set on keyboard 47 Make a forward turn of Operating Crank Change keyboard to read 43 Make a forward turn of Operating Crank Change keyboard to read -40 Make a backward turn of Operating Crank In lower dials "50" Answer 11 MULTIPLICATION Multiplication is a series of additions and is a simple process on the Monroe Model LN . It is accomplished by setting one figure (usually the larger) on the keyboard and "writing" the other figure in the upper dials with the operating crank. The repeat key must be depressed when doing multiplication. Example: 12 x 12 “ 144 Method: Repeat key depressed. Clear machine. Step 1. With the carriage in position "1", set 12 on the extreme right of the keyboard. Turn the Operating Crank forward 2 turns. Note • Step 2. With the Carriage Shift Lever, shift the carriage one place to the right. Turn the operating Crank forward one turn. Result: Upper dials 12 Keyboard 12 Lower dials 144 (answer) This gives a complete and positive check of accuracy. If the correct numbers show in the upper dials and keyboard, the answer cannot be incorrect. • If too large a number is turned into one of the upper dials, it can easily be corrected. Simply position the carriage so the carriage position arrow points to the incorrect dial and turn the operating crank backward until the correct number appears. If the incorrect number is too small, turn the crank forward until it is correct. i CONSTANT MULTIPLIER The above explanation of correcting the upper dials naturally leads to the problem where we have to multiply the same number by sev¬ eral different numbers. 12 In the previous example, we multiplied 12 x 12. Suppose we also had to multiply 12 by 31, and 12 by 15. After completing the first multiplication, the machine reads as follows: upper dials, 12; key¬ board, 12; lower dials, 144. It is not necessary to clear the machine. Leave the 12 on the key¬ board and simply change the upper dials to the next multiplier. Example: 12 x 31 “ 372 12 x 15 - 180 Method: Machine reads as stated above. Step 1. Clear nothing. Change the 1 in the upper dials to 3 with two forward turns of the Operating Crank. V . . Step 2. Shift carriage one place to the r+ght. Change 2 in the upper dials to 1 with one backward turn of Operating Crank. Result: Upper dials Keyboard Lower dials 31 12 372 (answer) Step 3. In a similar manner, change the upper dials to 15 and we have: Result: Upper dials Keyboard Lower dials 15 12 180 (answer) This entire operation is extremely simple. It requires no expert knowledge, skill or training, and you know your result is absolutely accurate because all the figures used are visible in the machine. It can be seen from the above that multiplication can be done in either direction. As long as the figures on the keyboard and in the upper dials are correct, the result in the lower dials will be correct. 13 DIVISION Division is just as easy and simple as multiplication. As multipli¬ cation is a process of repeated additions, accomplished by forward turns of the operating crank, so division is a process of continued subtractions, and is accomplished by backward turns of the opera¬ ting crank. The repeat key must be depressed when doing division. Example: 1728 * 12 “ 144 Method: Repeat key depressed. Clear machine. Step I. With the carriage in position "1", set the dividend, 1728, on the extreme right of the keyboard. Make one forward turn of the Operating Crank. Depress the Key¬ board Clear Key and turn Clear-out Crank clockwise. (This clears the keyboard and clears the "1" out of the upper dials.) Step 2. Set the divisor, 12, on the right of the keyboard and move the carriage two spaces to the right so that the divisor, 12, is in direct alignment with 17, the first two figures of the dividend in the lower dials. NOTE: In division problems, the left hand figure of the divisor on the keyboard must always be either directly under the left hand figure of the divi¬ dend in the lower dials, or beyond it to the left. Step 3. Turn the Operating Crank backward until the bell rings. Turn the Crank forward one turn. (The red 1 in the upper dials is the first digit of the answer.) Shift the carriage one place to the left. Turn the Crank backward until the bell rings. Turn the Crank forward one turn (bell also rings on the one forward turn to warn you not to go any farther). Step 4. Continue this operation of shifting the carriage one place to the left, turning the Crank back until the bell rings and turning the Crank forward one turn. Result: Lower dials 0 (remainder) Upper dials 144 (answer) 14 If the operator is turning the crank backward rapidly and goes a turn or two past the bell, he should simply turn the crank forward until the bell tings, and stop. Listening for these bells makes it possible to perform the division without watching the machine. PRACTICE PROBLEMS 1 . 510 -5- 15 — 34 2. 1400 -5- 25 = 56 3. 2432 + 32 = 76 4. 1659 -5- 237 = 7 5. 1464 -5- 122 = 12 6. 4830 -5- 14 = 345 7. 928 -5- 232 = 4 8. 1160 * 145 = 8 9. 1274 * 98 - 13 10. 510 -5- 85 - 6 Note: Be sure to clear the "1” from the upper dials and line up the lower dial figure and keyboard figure. 15 DECIMALS \ On all calculating machines, fractions are expressed as decimals. For example, 1/4 = .25, 5/8 ■ .625, etc. The arrangement of the dials and the keyboard on the Monroe makes it particularly adaptable to handling calculations involving decimal numbers. On the Monroe , all decimals can be set for a complete group of problems before starting the work, and all the calculations can be completed without any resetting of the decimals. The work is done entirely around pre-set, fixed decimals. The one simple rule for setting decimals on the Monroe is: Keyboard decimal + upper dial decimal “ lower dial decimal Decimal Markers The keyboard decimal is marked by turning one of the small knurled wheels below the keyboard to the right so that the yellow decimal marker appears between the proper keyboard columns. The upper and lower dials decimals are marked by the gray pointers which can be easily positioned to point off the decimal exactly as w r ith paper and pencil. To set a decimal at 2 in the dials, simply set the marker to the left of the 2 on the slide. 16 ADDITION AND SUBTRACTION OF DECIMAL NUMBERS To pre-set the decimals for a group of problems involving addition and subtraction, examine the numbers in all the problems and de¬ termine which has the largest number of decimal places. Set the keyboard decimal marker to accommodate this number of decimal places. Set the lower dials decimal at the same number. The upper dials decimal is at zero (0) and therefore the Monroe rule, as stated above holds. Following these instructions, what is the correct decimal setting for the following problems? 12.25 3.333 10.2 25.783 The correct decimal setting is: Upper dials 0 Keyboard 3 Lower dials 3 because 3 is the greatest number of decimal places which appears in these figures. Set these numbers on the keyboard exactly as they are written. The figures which appear to the left of the decimal point should be set to the left of the keyboard decimal marker, and those which appear to the right of the decimal should be set to the right of the keyboard decimal marker. Following the instructions for addition and sub¬ traction, given on page 11, the result will always be correct. PRACTICE PROBLEMS 152.45 160.0 - 75.242 237.208 13.00 36.60 -44.30 26.26 31.56 31.35 42.50 1.46 23.59 98.90 -3.46 1.56 - 21.20 35.45 12.35 17 MULTIPLICATION OF DECIMAL NUMBERS Handling decimal numbers in multiplication is also very simple. As you remember from the previous instructions, to multiply on the Monroe Model LN, you set the larger number on the keyboard and, with the operating crank, turn the other number into the upper dials. When this is done, the answer appears in the lower dials. Therefore, when multiplying decimal numbers, you should set the keyboard decimal marker to accommodate the largest number in the problem and the upper dials decimal marker to accommodate the other number. Then, following the Monroe rule for decimals, add the number of decimal places on the keyboard to the number of decimal places in the upper dials and set the lower dials decimal marker at this number of decimal places. This is exactly how you point off the decimal when multiplying by pencil and paper - add the number of decimal places in the two numbers and point off this many places in the result. All decimal markers should be set before beginning any of the work. What is the correct decimal setting for the following example? 20.125 x .425 - 8.553125 The larger number (20.125) will be set on the keyboard. It has three decimal places so the keyboard decimal marker should be set at 3* The other number (.425) will be entered in the upper dial, so set the upper dials decimal at 3. Add the two (3 + 3 = 6) and set the lower dials decimal at 6. Set the decimal markers accordingly and do the example following the step by step instructions below. Method: Upper dials decimal 3 Keyboard decimal 3 Repeat key depressed Lower dials decimal 6 Step 1. Set 20.125 on the keyboard (20 to the left of the key¬ board decimal marker and .125 to the right). Step 2. With the carriage in position "1", turn the Operating Crank 5 turns forward. Shift the carriage one place to the right. Make 2 forward turns. Shift the carriage to the right. Make 4 forward turns. 18 Result: Upper dials Lower dials .425 8.553125 Answer Note that the .425 appears in the upper dial to the right of the decimal marker and the lower dials decimal marker correctly points off the answer. We should always set the decimal for a whole group of problems to avoid changing the decimal markers for every problem. To do this for a group of multiplication problems, simply find the largest num¬ ber of decimal places appearing in the numbers to be set on the keyboard. Set the keyboard decimal marker for this number. Find the largest number of decimal places to be entered in the upper dials. Set the upper dial decimal for this number. Follow the Monroe rule and set the lower dials decimal at the sum of these two. Enter all figures around these pre-set decimals and the results will all be correct. The following example illustrates this. 24.75 x .35 - 8.6625 32.5 x .24 - 7.8 110.333 x 1.4 - 154.4662 The largest number of decimal places in the numbers which go on the keyboard is 3; in numbers which go in the upper dials is 2, and therefore, the decimal setting should be: Upper dials 2 Keyboard 3 Lower dials 5 Try the above problems and check the given answers to see if you are correct. 19 DIVISION OF DECIMAL NUMBERS In division, as explained in the instructions for simple division, both numbers, (dividend and divisor) are set on the keyboard. There¬ fore, when working with decimal numbers, we simply examine all the numbers to find the largest number of decimal places appearing in the whole group of problems at hand,. Set the keyboard decimal at this number. To set the upper dials decimal always decide how many decimal places are required in the answer and set the decimal marker to one more place than this (to permit rounding off). Again, for the lower dials decimal, add the keyboard and upper dials decimal and set the lower dials decimal at this number. Example: 22.868 v 6.7 ** 3*413 (rounded off) 12.33 -r 4.25 = 2.901 (rounded off) 5.56 -r .66 *= 8.424 (rounded off) Three is the greatest number of decimal places appearing in all the numbers in this group of problems. Set the keyboard decimal at 3. We require 3 decimal places in the answers, so set the upper dials decimal at 4 (3 + 1 =4). Then the lower dials decimal is 7 (3 + 4 =7). Step by step instructions for the first problem follows. Try the last two by yourself. Method: Upper dials 4 Keyboard 3 Repeat key depressed Lower dials Step I. Set 22.868 on the keyboard. Shift the carriage so the lower dial decimal at 7 is in direct alignment with the keyboard decimal at 3- Turn the Operating Crank for¬ ward one turn. Make one forward turn of the Clear-out Crank to clear 1 from the upper dials. Depress the Keyboard Clear Key. Step 2. Set 6.7 on the keyboard. Shift the carriage one place to the right. (To align the left hand digit in the lower dials with the left hand digit on the keyboard). 20 Step j. Turn the Operating Crank backward until the bell rings. Make one forward turn. Shift the carriage one place to the left. Step 4. Continue as in Step 3 until the carriage reaches the first position. Result: Upper dials 3.4131 (or 3.413 rounded off) Do the last two problems and check the answers above for accuracy. PRACTICE PROBLEMS Results are rounded off to two (2) decimal places. 1. 128.43 -5- 29.5 = 4.35 2. 962.99 -5- 37.3 = 25.82 3. 26.938 + 2.45 = 11.00 4. 63.824 -5- 5.75 = 11.10 5. 16.50 -5- .573 = 28.80 Note: Be sure to line up the lower dials deci¬ mal with the keyboard decimal before setting the first number in the lower dials. 21 MpNROE ® & ' /calculating WCbcAiK&l /ADDING 'ACCOUNTING 'DATA processing m^nr<3e { s/ To find the Square Hoot of a number using the Monroe Calculating Machine. Take the number 3.03 as an example. 0 Take out odd numbers from under the first (far left hand) 3 in the above number, until the figure 3 is reached (i.e. 1, 3 etc.) this is too high, so wind back to previous figure and press the next key below the figure 3 i.e. the figure 2 in this case and move the carriage to the left one digit and press the odd number key in the next row to the right until the figure 9 i3 reached i.e. 21, 23, 25, 27 , and the number 29 is read. Fow instead of the figure 2 press down figure 3 and instead of the figure 9, press down the figure 1 thus giving the number 31 on the keyboard and then continue to take out odd numbers in the right hand line of keys, thus 33, 35, now 35 is too high so wind back on the handle to the last figure //w the top window which in this case is 1.7, press the key No.4 instead of 5 also pressing the key Fo.1 in the next right hand column, and move the carriage to the left one digit thus the number 341 appears on the keyboard and continue to press down the odd number; keys on the right hand column thus 343, 345, 347, until the number 349 is reached this is too high, so come back to 348 press down the key Fo.1 on the next right hand column thus giving 3481 on the keyboard, move the carriage another digit to the left now 1.74 is in red figures in the top window, now 3481 on the keyboard is too high, so come back to 3480 move up one more digit to the left on the carriage and take out odd numbers in the next right hand column. Thus giving 34801, 34803, 34805, 34807, 34-809 continue to take out odd numbers thus 34811, 34813, which is too high,come back to 34812 move carriage to left one digit and in the top window the number 1.74-06 should appear. In the next available right hand column press down the odd number keys thus giving 348121, 348123, 348125, 348127, 348129, 348131, 348133, 34-8135, 34-8137, this last number is too high, so come back to 348136 and the number 1.74068 in Red in the top window. Move the carriage to the left one more digit continue to take out odd numbers in the next right hand column thus giving 3481361, 3481363, 3481395, 3481367, 34-81369, 3^81371, 3481373, 3481375, 3481377, 3481379 the last figure here is too high, so wind back one, giving the answer to 3*03^ as 1.740689. NCI TEL: - P\LL NC=> OPERATIONS f\R£. ThT -Sfl/vl EL FOR D/I//J/QA/