Răspuns:
Explicație pas cu pas:
a) 8 × 57 = 8 × ( 50 + 7) = 8 × 50 + 8 × 7 = 400 + 56 = 456
9 × 45 = 9 × (40 + 5 ) = 9 × 40 + 9 × 5 = 360 + 45 = 405
6 × 43 = 6 × (40+3) = 6 × 40 + 6 × 3 = 240 + 18 = 258
2 × 85 = 2 × ( 80 + 5 ) = 2 × 80 + 2 × 5 = 160 + 10 = 170
7 × 36 = 7 × ( 30 + 6 ) = 7 × 30 + 7 × 6 = 210 + 42 = 252
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b) 9 × 63 = 9 × ( 60 + 3 ) = 9 × 60 + 9 × 3 = 540 + 27 = 567
89 × 4 = ( 80 + 9 ) × 4 = 80 × 4 + 9 × 4 = 320 + 36 = 356
5 × 73 = 5 × ( 70 + 3 ) = 5 × 70 + 5 × 3 = 350 + 15 = 365
7 × 54 = 7 × ( 50 + 4 ) = 7 × 50 + 7 × 4 = 350 + 28 = 378
10 × 68 = 10 × ( 60 + 8 ) = 10 × 60 + 10 × 8 = 600 + 80 = 680
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produs de 2 factori
-> factorul de 2 cifre l-am scris ca suma de zeci si unitati
-> al inmultit fiecare termen al sumei cu factorul ramas de o cifra
-> apoi am insumat produsele obtinute
->am aplicat distributivitatea inmultirii fata de adunare
