Tính nhanh: 4 × 5 × 1/5 × 1/2 × 2
Giải thích
4 × 5 × \(\frac{1}{5}\) × \(\frac{1}{2}\) × 2
= 4 × \(\left( {5 \times \frac{1}{5}} \right) \times \left( {\frac{1}{2} \times 2} \right)\)
= 4 × 1 × 1
= 4
4 × 5 × \(\frac{1}{5}\) × \(\frac{1}{2}\) × 2
= 4 × \(\left( {5 \times \frac{1}{5}} \right) \times \left( {\frac{1}{2} \times 2} \right)\)
= 4 × 1 × 1
= 4