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    E:\Working\Orange_Education\TouchPad_Maths_4\Open_Files\Chap_02\Chap_02
                 \ 10-Nov-2025  Bharat Arora   Proof-8                                     Reader’s Sign _______________________ Date __________

                EStiMAtiNg thE SuM

                Sometimes we are not required to find the exact sum of numbers. An estimated sum
                fulfills our purpose in these cases. We round off the numbers to find the estimated sum.
                The estimated sum and the actual sum are different but are quite close to each other.

                Example. Find the estimated sum to the nearest 100 of the following numbers.
                             a.  275 + 538                                b.  1453 + 2107

                Solution.  a.         H T O                     H T O
                                      2 7 5      rounded        3 0 0
                                   +  5 3 8      rounded    +   5 0 0

                                      8 1 3                     8 0 0

                                             Actual sum        Estimated sum

                             b.       Th  H T O                    Th  H T O
                                      1   4 5 3     rounded        1   5 0 0
                                   +  2   1 0 7     rounded     +  2   1 0 0

                                      3   5 6 0                    3   6 0 0

                                                 Actual sum             Estimated sum

                            Exercise 2B

                    1.  Estimate each sum by rounding numbers to the nearest 10. Also find the actual sum.

                        a.  95 + 34              b.  273 + 158            c.  325 + 428            d.  4362 + 1537
                        e.  2431 + 2352          f.  1634 + 2158          g.  34902 + 41085        h.  24425 + 54351

                    2.  Estimate each sum by rounding numbers to the nearest 100. Also find the actual sum.
                        a.  956 + 538            b.  289 + 765            c.  601 + 572            d.  9860 + 4522
                        e.  7014 + 6678          f.  45329 + 9324         g.  23482 + 48599        h.  21702 + 15096

                AdditioN WoRd PRoBLEMS

                Example  1. The population  of City  A is 25301;  population  of City  B is 35701 and
                population of City C is 29032. What is the total population of the three cities?

                Solution. Population of City A =            2 5 3 0 1

                            Population of City B =          3 5 7 0 1
                            Population of City C = + 2 9 0 3 2
                            Total population          =    9 0 0 3 4

                The total population of the three cities is 90034.

                       30        Mathematics 4

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