Your CURTA Calculator

1 YourCURTAC alculatorPage1 YourCURTAC alculatorisahigh-qualityprecisioninstrum ent,fittedwithautomaticsafetylockstoprev entoperator ,toobtainbestresultsandefficientservicef romyourmachine, ;allyouhavetodoistofollow,stepbystepandi nthesequencesetout, ,it (8x6x11digits)andCURTA modelII(11x8x15digits).Thesetwomodelsbei ngidenticalbutfortheircapacity, ,holdthemachineinyourlefthand,withthumba ndforefingergrippingtheupperknurledringa ndthebaseofthemachinerestinginthepalmofy ourhand(seepictureonpage1).Page42 TheClearingLeverWhenpulledoutasindicated bythearrow, , TheOperatingHandleTurnthehandleclockwise only (showingawhiteorredsleeveatitsbase)forsu btractive(minus)turns,orpusheddownagaini nitslowerornormalpositionforadditive(plu s) (plusturns)andalsopulledoutinitsupperpos ition(minusturns).Tofinishdon Thecarriageistheupperknurledringofthemac hinewhichyougripwiththumbandforefinger(s eepictureatleft).Thewhitearrowonthefront ofthemachineindicatesthepositionsoftheca rriage, ,makesurethehandleisinitszerostoppositio n,raisethecarriagestraightupward, ,learntomovethecarriageonlywiththumbandf orefingerofyourlefthand(inwhichyouholdth emachine):Startingfromposition1movetheca rriagetopositions2,3,4,5, ,theyareintheirzeroposition, ,anynumberfrom1 ,eachdigitissetwithoneoftheknobs, :Withthethumbofthelefthandortheforefinge roftherighthandpullknob1rightdownuntilth e9appearsinthedialslotabove;withknob2set the 4 andwithknob3the 1.

2 ,thewhitedialisthecounterorquotientdial( seepictureatleft).7 Clearingthedialsisdonewiththeclearinglev er(seepictureatleft),whichhastwostopposi tions(AandB), , :Afterclearing,theclearinglevermustalway sbelocatedinoneofitstwostoppositions(Aor B), , ,raisethecarriageaspreviously,thenmoveth eclearingleveraroundtherespectivedial(bl ackorwhite) Thereversingleveratthebackofthemachineha stwoworkingpositions:theupperisthenormal positionforallcurrenttypesofcalculations ;theloweristobeusedonlyinspecialcases,pa rticularlyforsubtractions, : Carriage Carriagepositionindicatorarrow Carriagepositionnumbering Clearinglever Clearingleverreleasebutton Counterorquotientdial(white) Decimalmarker Operatinghandle Resultorproductdial(black) Settingdial Settingknobs SettingregisterPage12 SalesAgency: (viaSwitzerland)Page13 The4 , , , , :54x3=? ! :withknob1setthe 4 andwithknob2setthe 5 :eachturnofthehandletransfersthesetnumbe ronceintotheblackdial(resultdial).Themul tiplier3isthereforedevelopedwith3plustur ns(lowerornormalpositionofthehandle),whi chwillberegisteredinthewhitedial(counter dial).

3 Answer:Blackdial:162 Check:Settingdial:54,Whitedial:3647x125= ? ! :withknobs1to3set 647 . ,youwillnoticethata5hasbeendeveloped, :position3(hundredsdigit). :Blackdial:80875 Check:Whitedial:125,Settingdial:647 Page15 ! :withknobs1to3set 136 .Formarkingthedecimalpointuseoneofthewhi temobiledecimalmarkers(seepicture viewoftheCURTA ,page11). +2= : : , :457x89=? ! :withknobs1to3set 457 .Normallywewouldnowmake9turnsofthehandle withthecarriageinposition1and8turnswitht hecarriageinposition2, ,however, (100 11)or( 11+100).Wethereforecalculate457x( 1 10+100). :1minusturn(withhandleinupperposition):= :1minusturn:= :1plusturn(withhandledowninitsnormalposi tion):=+100 Answer:Blackdial:40673 Check:Whitedial:89,Settingdial:457 Thisshort-cutmethodisrecommendedwhenever thenumberstobedevelopedforthemultipliera re6,7,8, :237+419=? ! :withknobs1to3set 237 . :withknobs1to3set 419 . :Blackdial:656 Check:Whitedial:2,(Numberofitemsadded)Su btraction:139 78=? ! :withknobs1to3set 139 . :withknobs1and2set78; :1minusturn(withhandleinupperposition).

4 Answer:Blackdial:61**Remark:Ifacheckofth enumberofitemsaddedandsubtractedisrequir edthereversinglever(seesection8,page10) + ! . :withknobs1to3set ; :withknobs1to3set . : :42/7=?(Dividend)/(Divisor)=(Quotient) !(reversingleverinupperposition!). :withknob1set 7 (Divisor). :whilewatchingtheblackdialmakeplusturnsu ntilthedividend42appearsintheblackdial.( Ifbydoingaturntoomanyyouoversteptherequi reddividend, ,youwillhavetomakeeachtimeaminusturnimme diately.)Assoonasthenumber42(dividend) :Whitedial:6(quotient)Check:Blackdial:42 (dividend),Settingdial:7(divisor)Fordivi sionsgivingquotientswithseveraldigits,be foreoperatingyouplacethecarriageintooneo fitshigherpositions, ,forinstance, ,toavoidunnecessarythinking,thegeneralru letofollowistostarteverydivisionwiththec arriageinitshighestposition( ).Assoonastherequireddegreeofaccuracy(nu mberofdigits)forthequotienthasbeenattain ed,orwhenthedivisionfinishes,youbreakoff thecalculation, ! :withknobs1and2set 12 . :placeinitshighestposition( , ).

5 , ( ) ( ). :placeinthenextlowerposition( ; ). :after5plusturnsthefirstthreehighestdigi tsofthedividend( )havebeenoverstepped, ( ) :placeinthenextlowerposition( ; ). :setadecimalmarkerafterthelastwholenumbe rofthedividend,thatisimmediatelybehindth e 8 .Inthesettingdialwehavethewholenumber12; :thedecimalsintheblackdial(dividend)minu sthedecimalsinthesettingdial(divisor)giv ethenumberofdecimalsinthewhitedial(quoti ent).InthiscasewithCURTAI wefind3 0=3decimalplacesandwithCURTAII5 0= :setadecimalmarkerimmediatelybehindthela st4of144, : (quotient)Check:Blackdial:1728(dividend) ,Settingdial:12(divisor) , ! (1728/12) :after5plusturns,theblackdialshowing1740 , :after1plusturn,theblackdialshowing17292 , :after9plusturns,theblackdialshowing1729 08, :after4plusturns,theblackdialshowing1729 008, ,sincethecarriagecanbemovedto2furtherpos itions( ). :4plusturns, :4plusturns, :Setthedecimalmarkers:inthesettingdialbe tweencolumns2and1( ),andintheblackdialimmediatelyafterthela stwholenumberofthedividend,thatisbehindt he 7 ( ).

6 Applyingthedecimalrulewefindforthewhited ialofCURTAI5 1=4decimalplaces,andforthatofCURTAII7