Вычисли наиболее простым способом:
16 + 40
17 + 39
18 + 38
19 + 37
84 − 60
84 − 59
84 − 58
84 − 57
39 − 19
40 − 19
41 − 19
42 − 19
16 + 40 = (10 + 6) + 40 = (40 + 10) + 6 = 50 + 6 = 56;
17 + 39 = (16 + 1) + (40 − 1) = 16 + 40 = 56;
18 + 38 = (16 + 2) + (40 − 2) = 16 + 40 = 56;
19 + 37 = (16 + 3) + (40 − 3) = 16 + 40 = 56.
84 − 60 = (80 + 4) − 60 = (80 − 60) + 4 = 20 + 4 = 24;
84 − 59 = 84 − (60 − 1) = (84 − 60) + 1 = 24 + 1 = 25;
84 − 58 = 84 − (60 − 2) = (84 − 60) + 2 = 24 + 2 = 26;
84 − 57 = 84 − (60 − 3) = (84 − 60) + 3 = 24 + 3 = 27.
39 − 19 = (30 + 9) − (10 + 9) = (30 − 10) + (9 − 9) = 20;
40 − 19 = (39 + 1) − 19 = (39 − 19) + 1 = 20 + 1 = 21;
41 − 19 = (39 + 2) − 19 = (39 − 19) + 2 = 20 + 2 = 22;
42 − 19 = (39 + 3) − 19 = (39 − 19) + 3 = 20 + 3 = 23.