Номер 686

22 · 4 = (20 + 2) · 4 = 20 · 4 + 2 · 4 = 80 + 8 = 88;
24 · 3 = (20 + 4) · 3 = 20 · 3 + 4 · 3 = 60 + 12 = 72;
34 · 5 = (30 + 4) · 5 = 30 · 5 + 4 · 5 = 150 + 20 = 170;
17 · 5 = (10 + 7) · 5 = 10 · 5 + 7 · 5 = 50 + 35 = 85;
42 · 7 = (40 + 2) · 7 = 40 · 7 + 2 · 7 = 280 + 14 = 294;
38 · 2 = (30 + 8) · 2 = 30 · 2 + 8 · 2 = 60 + 16 = 76.