Tính nhanh: a, 4130 + 4130 + 4130 + 319 + 319 + 319

* Hướng dẫn giải

a, 4130 + 4130 + 4130 + 319 + 319 + 319

 = 4130 × 3 + 319 × 3

 = (4130 + 319) × 3

 = 4449 × 3

 = 13347

b, 1052 + 1052 – ( 286 + 286 + 286)

 = 1052 × 2 – 286 × 3 = 2104 – 858

 = 1246

c, 2020 + 2020 + 2010 + 2010 + 56 + 56

 = 2020 × 2 + 2010 × 2 + 56 × 2

 = (2020 + 2010 + 56) × 2

 = 4086 × 2

 = 8172

d, 2830 + 2830 + 2830 + 2830 +2830 = 2830 × 5 = 14150a