a) 48 · 999 = 48 · (1000 - 1) = 48 · 1000 - 48 · 1
= 48000 - 48 = 47952
b) 999 · 547 = (1000 - 1) = 1000 · 547 - 1 · 547=
= 547000 - 547 = 546453
c) 205 · 101 = 205 · (100 + 1) = 205 · 100 + 205 · 1 =
= 20500 +205 = 20705
d) 123 · 1001 = 123 · (1000 + 1) = 123 · 1000 + 123 · 1 =
= 123000 + 123 = 123123
