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Measure - Standard units of mass (g, kg)

Grade 3Cambridge (IGCSE)

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Mass is the measure of how heavy an object is.

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The two standard units of mass are grams (g) and kilograms (kg).

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Grams (g) are used to measure light objects like a paperclip, a pencil, or a grape.

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Kilograms (kg) are used to measure heavier objects like a watermelon, a suitcase, or a person.

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We use weighing scales (digital or analogue) to measure mass.

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When reading an analogue scale, it is important to check the value of the small marks (intervals) between the numbers.

📐Formulae

1 kg=1000 g1 \text{ kg} = 1000 \text{ g}

12 kg=500 g\frac{1}{2} \text{ kg} = 500 \text{ g}

14 kg=250 g\frac{1}{4} \text{ kg} = 250 \text{ g}

To convert kg to g→Multiply by 1000\text{To convert kg to g} \rightarrow \text{Multiply by } 1000

To convert g to kg→Divide by 1000\text{To convert g to kg} \rightarrow \text{Divide by } 1000

💡Examples

Problem 1:

Convert 4 kg into grams.

Solution:

4000 g

Explanation:

Since 1 kg=1000 g1 \text{ kg} = 1000 \text{ g}, we multiply the number of kilograms by 1000. 4×1000=40004 \times 1000 = 4000.

Problem 2:

Sarah has a bag of flour that weighs 1 kg. She uses 350 g to bake a cake. How much flour is left in the bag?

Solution:

650 g

Explanation:

First, convert the 1 kg bag into grams: 1 kg=1000 g1 \text{ kg} = 1000 \text{ g}. Then subtract the amount used: 1000 g−350 g=650 g1000 \text{ g} - 350 \text{ g} = 650 \text{ g}.

Problem 3:

Which is heavier: 2500 g or 2 kg?

Solution:

2500 g

Explanation:

To compare, convert both to the same unit. 2 kg=2000 g2 \text{ kg} = 2000 \text{ g}. Since 2500 g2500 \text{ g} is greater than 2000 g2000 \text{ g}, 2500 g2500 \text{ g} is heavier.

Problem 4:

A scale has markings every 100g. If the needle is halfway between 400g and 500g, what is the mass?

Solution:

450 g

Explanation:

The distance between 400 and 500 is 100. Half of 100 is 50. Therefore, 400+50=450 g400 + 50 = 450 \text{ g}.

Standard units of mass (g, kg) Grade 3 Notes & Examples