Частина 1. Номер 71

Виконай додавання способом округлення.

48 + 39 = 48 + (40 – 1) = 48 + 40 – 1 = 87;

67 + 51 = (70 – 3) + 51 = 70 – 3 + 51 = 118;

36 + 47 = 36 + (50 – 3) = 36 + 50 – 3 = 83;

48 + 23 = (50 – 2) + 23 = 50 – 2 + 23 = 48 + 23 = 71;

55 + 18 = 55 + (20 – 2) = 55 + 20 – 2 = 75 – 2 = 73;

69 + 11 = (70 – 1) + 11 = 70 – 1 + 11 = 69 + 11 = 80;

23 + 79 = 23 + (80 – 1) = 23 + 80 – 1 = 103 – 1 = 102;

57 + 12 = (60 – 3) + 12 = 60 – 3 + 12 = 57 + 12 = 69.