1) Закончи вычисления.
54 * 15 = 54 * (10 + 5)
214 * 20 = 214 * (2 * 10)
30 * 28 = 30 * (20 + 8)
30 * 28 = 28 * (3 * 10)
2) Вычисли.
16 * 13
17 * 40
60 * 12
54 * 15 = 54 * (10 + 5) = 54 * 10 + 54 * 5 = 540 + 270 = 810
214 * 20 = 214 * (2 * 10) = (214 * 2) * 10 = 428 * 10 = 4280
30 * 28 = 30 * (20 + 8) = 30 * 20 + 30 * 8 = 600 + 240 = 840
30 * 28 = 28 * (3 * 10) = (28 * 3) * 10 = 84 * 10 = 840
16 * 13 = 16 * (10 + 3) = 16 * 10 + 16 * 3 = 160 + 48 = 208
17 * 40 = 17 * (4 * 10) = (17 * 4) * 10 = 68 * 10 = 680
60 * 12 = 12 * (6 * 10) = (12 * 6) * 10 = 72 * 10 = 720
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