Номер 1277

1) –99 • 17 = (1 – 100) • 17 = 1 • 17 – 100 • 17 = 17 – 1700 = –1683;

2) –12 • 101 = –12 • (100 + 1) = –12 • 100 – 12 • 1 = –1200 –12 = –1212;

3) –999 • (–13) = (1 – 1000) • (–13) = 1 • (–13) – 1000 • (–13) = –13 + 13000 = 12987;

4) –1001 • 29 = –(1000 + 1) • 29 = –(29 • 1000 + 29 • 1) = –(29000 + 29) = –29029.