Страница 30
Устный счет
Задание 1.
75 + 23 = (75 + 20) + 3 = 95 + 3 = 98
75 + 20 = 95
75 + 3 = 78

75 – 23 = (75 – 20) – 3 = 55 – 3 = 52
75 – 20 = 55
75 – 3 = 72

35 + 10 = 45
45 + 11 = (40 + 10) + (5 + 1) = 50 + 6 = 56
56 + 12 = (56 + 10) + 2 = 66 + 2 = 68

43 + 10 = 53
53 + 11 = (53 + 10) + 1 = 63 + 1 = 64
64 + 12 = (60 + 10) + (4 + 2) = 70 + 6 = 76
76 + 13 = (76 + 3) + 10 = 79 + 10 = 89

77 – 10 = 67
67 – 11 = (67 – 10) – 1 = 57 – 1 = 56
56 – 12 = (56 – 10) – 2 = 46 – 2 = 44
44 – 13 = (44 – 10) – 3 = 34 – 3 = 31

89 – 10 = 79
79 – 11 = (79 – 10) – 1 = 69 – 1 = 68
68 – 12 = (68 – 10) – 2 = 58 – 2 = 56
56 – 13 = (56 – 10) – 3 = 46 – 3 = 43

Задание 2.
6 – 3 = 3
Последующее число на 3 больше предыдущего.
3 + 3 = 6
6 + 3 = 9
9 + 3 = 12
12 + 3 = 15
15 + 3 = 18
18 + 3 = 21
21 + 3 = 24
24 + 3 = 27
27 + 3 = 30
30 + 3 = 33
33 + 3 = 36