1. a one dollar coin 15 g b tree 300 kg c grain of sand 1 mg d tennis ball 75 mg e pair of shoes 100 g f small child 45 kg h pen 10 g i bowling ball 3 kg

 2. (i) The weight of a laptop computer − e − 3000 g (ii) The weight of a tennis player − d − 74 kg (iii) The weight of a litre of milk − a − 1 kg (iv) The weight of an AA size battery − b − 40 g (v) The weight of a small drop of liquid − f − 8 g (vi) The weight of a space rocket − c − 20 tonnes

 3. mg g kg 340 000 340 0.340 950 0.950 0.00095 2 600 000 2600 2.6

 4. a. 4 kg + 3 kg = 7000 gb. 2 kg + 546 g = 2546 gc. 8 g + 381 mg = 8.381 gd. 6390 mg + 493 g + 1.3 kg = 1 799.39 ge. 5 kg − 550 g = 4450 gf. 850 mg + 0.5 g − 550 mg = 0.8 g

 5. a. 55 mg 0.055 g b. 3kg 3 000 g c. 2400 mg 2.4 g d. 4.8 g 4 800 mg e. 438 mg 0.438 g f. 2.4 kg 2400 g g. 648 g 0.648 kg h. 320 g 320 000 mg i. 824 mg 0.824 g j. 5.9 kg 5 900 000 mg

 6 a. 176.298 kilogramsb. 176 298 gramsc. 0.176298 tonne

 7.a 6g , 1480 mg 7480 mg b 2 kg , 950 g 2950 g c 5 t , 3650 kg 8650 kg d 9500 kg, 8.2 t 17.7 t e 0.4 kg , 5320 mg , 30 g , 0.004 t 4435.32 g