Tính bằng cách thuận tiện.

a) 73 833 + 3 992 – 3 833

b) 85 600 + 2 500 – 5 600

c) 30 254 + 10 698 + 1 746

a) 73 833 + 3 992 – 3 833 = (73 833 – 3 833) + 3 992

                                            = 70 000 + 3 992 = 73 992

b) 85 600 + 2 500 – 5 600 = (85 600 – 5 600) + 2 500

                                            = 80 000 + 2 500 = 82 500

c) 30 254 + 10 698 + 1 746 = (30 254 + 1 746) + 10 698

                                              = 32 000 + 10 698 = 42 698