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                     276                         Fundamentals of Computers                          NPP

                                                9’s complement   = 99 – 42 = 57
                                                10’s complement  = 57 + 1   = 58
                        9’s complement and 10’s complements are     9’s H$m°påßb_|Q> VWm 10’s H$m°påßb_|Q> H$m Cn`moJ
                    used  for  subtraction  of  decimal    numbers  in  Xe_bd g§»`m H$mo KQ>mZo _| {H$`m OmVm h¡ Ÿ& BZ_| 10’s
                    electronic circuits. 10’s complement method is  H$måßbr_|Q> A{YH$ Cn`moJr h¡ Ÿ&
                    very important for us.

                    10’s Complement Subtraction Method          10’s H$m°påßb_|Q> _| KQ>mZo H$s {d{Y
                        The process of subtraction is done with the  KQ>mZo H$s {H«$`m H$mo Omo‹S>Zo _| n[ad{V©V {H$`m OmVm
                    help of addition. This method is based on rep-  h¡ Ÿ& Bg_| KQ>Zo dmbr g§»`mAm| H$mo 10’s H$m°påßb_|Q> _|
                    resenting subtrahend 10’s complement form.
                                                                n[ad{V©V {H$`m OmVm h¡&
                        Consider the following problem:             {ZåZ CXmhaU H$mo XoImo…
                                                           35  – 14
                        First find the 10’s complement of the sub-   nhbo F$UmË_H$ g§»`m 14 H$m 10’s H$m°påßb_|Q> bmo…
                    trahend 14
                                                9’s complement   = 99 – 14 = 85
                                                10’s complement  = 86
                        Replace  (–)  sign with (+) and put 10’s    A~ (-) H$s OJh (+) {bImo Am¡a 14 Ho$ ñWmZ
                    complement of 14:                           na CgH$m 10’s H$m°påßb_|Q> {bImo…

                                                                    35
                                                                 +  86
                                                    carry →   1     2 1

                        The carry at the end can be neglected. The  A§V _| Omo hm{gb Am ahm h¡, Cgo N>mo‹S> Xmo Ÿ& hm{gb
                    occurrence of the carry shows that the result is  H$m AmZm `h ~VmVm h¡ {H$ CÎma YZmË_H$ h¡ Ÿ& AV…
                    positive. Thus, the result is:
                                                        35 – 14 = + 21
                        Sometimes there will not be any carry gen-  H$^r-H$^r Omo‹S> Ho$ A§V _| hm{gb Zht AmEJm Ÿ&
                    erated at the end. This shows that  the result is  Bggo `h nVm MbVm h¡ {H$ n[aUm_ F$UmË_H$ h¡ Am¡a `h
                    negative  and it is in the 10’s complement form.  dmñV{dH$ n[aUm_ H$m 10’s H$m°påßb_|Q> h¡ Ÿ& AV… n[aUm_
                    To get the  actual result we take 10’s comple-  àmá H$aZo Ho$ {bE Omo `moJ Am`m h¡ CgH$m EH$ ~ma {\$a
                    ment of the sum,                            go 10’s H$m°påßb_|Q> b|Jo&

                        Consider the following problem:             {ZåZ CXmhaU H$mo XoImo…
                                                           39  – 85
                        Replace  (–)  sign  with  (  +  )  and  put  10’s  (-) H$s OJh (+) {bImo VWm 85 Ho$ ñWmZ na
                    complement of 85
                                                                CgH$m 10’s H$m°påßb_|Q> {bImo …
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