Răspuns:
Grupează numerele pentru a calcula rapid
a)
5 × 9 × 10 = (5 × 9) × 10 = 45 × 10 = 450;
6 × 2 × 5 = 6 × (2 × 5) = 6 × 10 = 60;
b)
12 × 3 × 10 = (12 × 3) × 10 = 36 × 10 = 360;
4 × 5 × 2 = 4 × (5 × 2) = 4 × 10 = 40;
c)
120 × 2 × 10 = (120 × 2) × 10 = 240 × 10 = 2400;
150 × 9 × 2 = (150 × 2) × 9 = 300 × 9 = 2700.