69
Kilograms and grams
Textbook: Part 3, lesson 69, pp. 4–6
GoalMeasure mass in grams and kilograms; 1 kg = 1 000 g; convert between the units, add and subtract.
New words
mass · massascales · tarozigram · gramm (g)kilogram · kilogramm (kg)
Explanation
Mass tells how heavy something is; it is measured on scales. Light things are measured in grams (g), heavier ones in kilograms (kg): 1 kg = 1 000 g. To go from kilograms to grams multiply by 1 000; to go from grams to kilograms divide by 1 000. When calculating with numbers like 3 kg 200 g it is easiest to change everything to the smallest unit, grams.
Worked examples
3 kg 200 g = 3 000 g + 200 g = 3 200 g; 5 620 g = 5 kg 620 g.
7 kg 450 g − 2 kg 80 g = 7 450 g − 2 080 g = 5 370 g = 5 kg 370 g.
Class activity
“Market scales”: in pairs, children estimate the mass of 3–4 items in kg and g, then change all to grams and find the total mass.
Practice
1
4 kg 75 g = ? g
4075
2
2 kg 350 g + 1 kg 750 g = ? g
4100
3
One sack of rice has a mass of 2 kg 500 g. How many grams do 4 such sacks weigh?
10000
4
Dilnoza bought 1 kg 800 g of grapes and 950 g of pomegranates at the market. How many grams did she buy in total?
2750
5
3 kg 600 g of meat was cut into 4 equal parts. How many grams is each part?
900