Răspuns:
Explicație pas cu pas:
8 × 9 = 7 × 9 + 9 = 63 + 9 = 72 → primul mod
8 × ( 4 + 5) = 8 × 4 + 8 × 5 = 32 + 40 = 72 → al doilea mod
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4 × 7 = 3 × 7 + 7 = 21 + 7 = 28
4 × ( 2 + 5 ) = 4 × 2 + 4 × 5 = 8 + 20 = 28
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7 × 9 = 6 × 9 + 9 = 54 + 9 = 63
7 × ( 4 + 5) = 7 × 4 + 7 × 5 = 28 + 35 = 63
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9 × 9 = 8 × 9 + 9 = 72 + 9 = 81
9 × ( 4 + 5) = 9 × 4 + 9 × 5 = 36 + 45 = 81
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7 × 10 = 6 × 10 + 10 = 60 + 10 = 70
7 × ( 5 + 5 ) = 7 × 5 + 7 × 5 = 35 + 35 = 70
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10 × 6 = 9 × 6 + 6 = 54 + 6 = 60
10 × 6 = 10 × ( 1+5) = 10 × 1 + 10 × 5 = 10 + 50 = 60
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6 × 6 = 5 × 6 + 6 = 30 + 6 = 36
6 × ( 1 + 5 ) = 6 × 1 + 6 × 5 = 6 + 30 = 36
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5 × 8 = 4 × 8 + 8 = 32 + 8 = 40
5 × ( 3 + 5 ) = 5 × 3 + 5 × 5 = 15 + 25 = 40
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4 × 6 = 3 × 6 + 6 = 18 + 6 = 24
4 × ( 1 + 5 ) = 4 × 1 + 4 × 5 = 4 + 20 = 24
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8 × 5 = 7 × 5 + 5 = 35 + 5 = 40
8 × ( 2 + 3 ) = 8 × 2 + 8 × 3 = 16 + 24 = 40
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10 × 10 = 9 × 10 + 10 = 90 + 10 = 100
10 × ( 5 + 5 ) = 10 × 5 + 10 × 5 = 50 + 50 = 100
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7 × 7 = 6 × 7 + 7 = 42 + 7 = 49
7 × ( 2 + 5 ) = 7 × 2 + 7 × 5 = 14 + 35 = 49
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9 × 10 = 8 × 10 + 10 = 80 + 10 = 90
9 × ( 5 + 5 ) = 9 × 5 + 9 × 5 = 45 + 45 = 90
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8 × 8 = 7 × 8 + 8 = 56 + 8 = 64
8 × ( 3 + 5 ) = 8 × 3 + 8 × 5 = 24 + 40 = 64
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1 × 7 = 0 × 7 + 7 = 0 + 7 = 7
1 × ( 2 + 5 ) = 1 × 2 + 1 × 5 = 2 + 5 = 7
