Odpowiedź:
zad 9
a)
8 * 17 = 8 * (10 + 7) = 8 * 10 + 8 * 7 = 80 + 56 = 136
b)
23 * 5 = (20 + 3) * 5 = 20 * 5 + 3 * 5 = 100 + 15 = 115
c)
4 * 57 = 4 * (50 + 7) = 4 * 50 + 4 * 7 = 200 + 28 = 228
d)
64 * 8 = (60 + 4) * 8 = 60 * 8 + 4 * 8 = 480 + 32 = 512