Tính nhẩm (theo mẫu): 7,98 + 2,48 = (7,98 + 0,02) + (2,48 – 0,02) = 8 + 2,46 = 10,46. a) 51,99 + 21,55; b) 17,31 – 1,96; c) 16,78 – 12,99; d) –15,95 – 31,72.
Tính nhẩm (theo mẫu): 7,98 + 2,48 = (7,98 + 0,02) + (2,48 – 0,02) = 8 + 2,46 = 10,46. a) 51,99 + 21,55; b) 17,31 – 1,96; c) 16,78 – 12,99; d) –15,95 – 31,72. | |
