Basic HTML Version

|  | Table of Contents |  | View Full Version

Page 66 - Touchpad Mathematics_Ver1.0_C4
P. 66

    Example 2. A shopkeeper had 662 balls. He sold 245 balls. Estimate the number of
                unsold balls by rounding to the nearest 10. Is the number of balls left unsold more
                than 400 or less than 400?
                Solution.      Actual difference               Estimated difference

                                    6 6 2         round off           6 6 0
                                – 2 4 5           round off       – 2 5 0

                                    4 1 7                             4 1 0

                Thus, the shopkeeper has more than 400 balls left unsold with him.

                                                                                                  21 st
                          Activity                                                              Century   #Experiential Learning
                                                                                                 Skills

                    Subtraction race to Zero or any other target number
                    Play with your partner. Choose any 3- or 4-digit number and write it on a sheet of paper.
                    For example: 1000
                    One player starts the game. He/she takes 2-3 dice and rolls them. Using the numbers
                    face up, form a 2- or 3-digit number.
                    Round off the number to the nearest 10 and then subtract it from
                    your chosen number.
                    Number formed = 326 and rounded off to 330
                    Then, 1000 – 330 = 670.

                    Similarly, the other player will take a turn and do the same process.
                    Then, the first player will repeat the process to get the next number and subtract it from
                    the number obtained in the previous step.
                    Continue the activity until one player reaches the number 0. The player who reaches the
                    target number, wins the game.

                            Exercise 3E

                First, find the actual difference. then, find the estimated difference by rounding to the
                nearest 10. Finally, compare both the results.
                    1.  87 – 23                                           2.   167 – 94

                                 Actual             Estimated                        Actual                  Estimated

                                  8 7                                                1  6 7
                              – 2 3                  –                           –      9 4                –

                       64        Mathematics 3

| 61 62 63 64 65 66 67 68 69 70 71 |