54 : 6 = 9; 4 · 9 = 36; 9 · 7 = 63; 63 : 7 = 9; 28 : 7 = 4; 4 · 7 = 28; 7 · 8 = 56; 72 : 9 = 8; 9 · 7 = 63; 8 · 8 = 64; 3 · 7 = 21; 28 : 4 = 7; 16 : 2 = 8; 7 · 3 = 21; 10 : 2 = 5; 40 : 5 = 8; 45 : 5 = 9; 9 · 3 = 27; 21 : 3 = 7; 72 : 8 = 9; 6 : 3 = 2; 30 : 5 = 6; 4 · 7 = 28; 16 : 4 = 4; 10 : 5 = 2; 2 · 6 = 12; 6 · 7 = 42; 30 : 6 = 5.