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    eSTiMATiNg THe proDuCT

                    We can find the estimated product by rounding off the numbers.

                    Example 1. Find the two estimated numbers between which the product of 48 and 4 will lie.
                    Solution. 48 comes between 40 and 50.
                                                                                                                      4 8
                                40 × 4 = 160    and    50 × 4 = 200                                            ×          4

                    So, the product of 48 and 4 comes between 160 and 200.                                         1 9 2

                    Let us check:                     48 × 4 = 192

                    Clearly, 192 lies between 160 and 200.
                    example 2. Find the estimated product: 73 × 26                                                    7 0

                    Solution. 73 rounded off to 70                                                         ×          3 0

                    26 rounded off to 30                                                                              0 0
                    Now:                           70 × 30 = 2100
                                                                                                           + 2 1 0 0
                    So, the estimated product = 2100.                                                          2 1 0 0

                                Exercise 4F

                        1.  find the two estimated numbers between which the product of the following numbers
                           will lie.
                           a.    28 × 4             b.    55 × 7              c.   64 × 3              d.   87 × 5

                           e.    46 × 9             f.    41 × 8              g.   44 × 6              h.   37 × 2
                       2.  find the estimated product as well as the actual product.

                           a.    55 × 24            b.    28 × 13             c.   63 × 34             d.   44 × 33
                           e.    58 × 22            f.    42 × 24             g.   73 × 19             h.   45 × 19

                    WorD proBleMS

                    example 1. A packet  contains  144  balloons. Find the  number  of
                    balloons in 24 such packets.
                                                                                                 1 4 4
                    Solution.                                                            ×          2 4

                    Number of balloons in one packet  = 144
                                                                                                 5 7 6
                    Number of packets                          = 24                      + 2 8 8 0

                    So, the number of balloons in 24 such packets                            3 4 5 6
                                                               = 144 × 24 = 3456

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                                                                                                 Multiplication

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