Номер 1270

1) 4 • (1/4 – 1/2) = 4 • 1/4 – 4 • 1/2 = 1 – 2 = –1

2) (–1/7 + 1/14 – 1/42) • 42 = – 1/7 • 42 + 1/14 • 42 – 1/42 • 42 = –6 + 3 – 1 = –4

3) 21 • (1/7 – 1/3 – 1) = 21 • 1/7 – 21 • 1/3 – 21 • 1 = 3 – 7 – 21 = –25 

4) –12 • (1/3 – 1/6) = –12 • 1/3 – 12 • (–1/6) = –4 + 2 = –2

5) 18 • (1/9 – 1/2 – 1/3) = 18 • 1/9 – 18 • 1/2 – 18 • 1/3 = 2 – 9 – 6 = –13

6) (1/25 – 1/2 – 1/5) • (–100) = 1/25 • (–100) – 1/2 • (–100) – 1/5 • (–100) = –4 + 50 + 20 = 66