Lời giải

a) 3 kg + 30 kg + 270 kg

= 3 kg + (30 kg + 270 kg)

= 3 kg + 300 kg

= 330 kg

b) 320 km + 32 km + 680 km + 68 km

= (320 km + 680 km) + (32 km + 68 km)

= 1 000 km + 100 km

= 1 100 km

c) 2 500 l + 2 900 l + 2 100 l + 2 500 l

= (2 500 l + 2 500 l) + (2 900 l + 2 100 l)

= 5 000 l + 5 000 l

= 10 000 l

Lời giải

a) 24 + 17 + 26 = (24 + 26) + 17

                          = 50 + 17

                          = 67

b) 80 + 310 + 120 = (80 + 120) + 310

                              = 200 + 310

                              = 510

c) 34 + 140 + 60 + 16 = (34 + 16) + (140 + 60)

                                    = 50 + 200

                                    = 250