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    Exercise 3D

                        1.  Subtract.

                           a.       8 6 5 2         b.       7 0 5 4          c.      8 4 0 5         d.      6 7 9 5
                                – 5 9 7 6                – 3 9 6 7                – 2 7 7 6               – 4 8 9 4

                           e.       6 4 0 0         f.       4 3 4 4          g.      4 6 7 5         h.      5 4 9 9
                                – 3 9 9 9                – 2 6 5 5                – 3 8 4 6               – 3 9 6 8

                       2.  Write in the columns and subtract.
                           a.    7467 – 5183        b.    4837 – 2639         c.   6549 – 3999         d.   5667 – 3994

                           e.    8777 – 4997        f.    9606 – 7397         g.   7237 – 2655         h.   8000 – 3968
                       3.  Fill in the boxes.

                           a.    273 – 0 = ______                             b.   564 – ______ = 564

                           c.    7364 – 0 = ______                            d.   575 – 1 = ______
                           e.    649 – ______ = 648                           f.   ______ – 1 = 276

                       4.  Subtract mentally:
                           a.    425 – 10 = ______                            b.   896 – 10 = ______

                           c.    567 – 100 = ______                           d.   4364 – 100 = ______

                           e.    2645 – 1000 = ______                         f.   5730 – 1000 = ______

                    EStIMAtIng tHE dIFFErEnCE

                    Like addition, we can also estimate the difference by using the concept of rounding off.

                    Example 1. Estimate the difference of 64 and 87 by rounding them to the nearest 10.
                    Then compare their actual difference and estimated difference.
                    Solution.      Actual difference           Estimated difference          Comparison

                                                  round off
                                       8 7                            9 0                        23 < 30
                                    – 6 4          round off      – 6 0

                                       2 3                            3 0

                    The estimated difference is greater than the actual difference.

                                                                                                                  63
                                                                                                  Subtraction

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