Завдання:
Обчисли (усно):
1) 572 ⋅ 10;
2) 100 ⋅ 7982;
3) 1000 ⋅ 52;
4) 8 ⋅ 7 ⋅ 5;
5) 7 ⋅ 20 ⋅ 5;
6) 4 ⋅ 91 ⋅ 25;
7) 43 ⋅ 125 ⋅ 8;
8) 5 ⋅ 9 ⋅ 2 ⋅ 6;
9) 10 ⋅ 2 ⋅ 7 ⋅ 50.
Розв'язок:
1) 572 • 10 = 5720
2) 100 • 7982 = 798 200
3) 52 • 1000 = 52 000
4) 8 • 7 • 5 = (8 • 5) • 7 = 40 • 7 = 280
5) 7 • 20 • 5 = 7 • (20 • 5) = 7 • 100 = 700
6) 4 • 8 • 25 = (4 • 25) • 8 = 8 • 100 = 800
7) 43 • 10 • 2 = (43 • 2) • 10 = 86 • 10 = 860
8) 5 • 9 • 2 • 7 = (9 • 7) • (5 • 2) = 63 • 10 = 630
9) 10 • 2 • 7 • 50 = (7 • 10) • (2 • 50) = 70 • 100 = 7000