Converting and Calculating Units of Mass

Metric units of mass are used to measure the weight of objects accurately. The most common mass units are:

• Milligrams (mg): Used for tiny objects like medicine pills.
  • 1 mg is about the weight of a grain of sand.
• Grams (g): Common for measuring food and small household items.
  • 1 g is about the weight of a paperclip.
• Kilograms (kg): Used for measuring people, cargo, or larger objects.
  • 1 kg is about the weight of a bag of rice.
• Tons (t): Used for very heavy objects like vehicles or shipping containers.
  • 1 t is about the weight of a small car.

To convert between mass units:

• Multiply by 1,000 when moving to a larger unit (mg → g → kg → t).
• Divide by 1,000 when moving to a smaller unit (t → kg → g → mg).

You need to remember these key conversions between units of mass:

• 1 mg = 0.001 g
• 1 g = 1,000 mg
• 1 kg = 1,000 g
• 1 t = 1,000 kg

🌟 Example 1: Converting 21 kilograms to grams

1. Kilograms to grams → Multiply by 1,000 (since 1 kg = 1,000 g).
2. $21 \times 1000 = 21,000$
3. So, 21 kilograms = 21,000 grams ✅

🌟 Example 2: Converting 560 kilograms to tonnes

1. Kilograms to tonnes → Divide by 1,000 (since 1 t = 1,000 kg).
2. $560 \div 1000 = 0.56$
3. So, 560 kilograms = 0.56 tonnes ✅

When calculating with different mass units, convert to the same unit first.

🌟 Example 1: Adding 3.25 kg and 30 g

1. Convert 30 g to kg:
   $30 \text{ g} = 0.03 \text{ kg}$
2. Add the values in kilograms:
   $3.25 \text{ kg} + 0.03 \text{ kg} = 3.28 \text{ kg}$
3. Final Answer: 3.28 kg ✅

🌟 Example 2: Subtracting 30 g from 3.25 kg

1. Convert 3.25 kg to g:
   $3.25 \text{ kg} = 3250 \text{ g}$
2. Subtract the values in grams:
   $3250 \text{ g} \ -\ 30 \text{ g} = 3220 \text{ g}$
3. (Optional) Convert back to kg:
   $3220 \text{ g} = 3.22 \text{ kg}$
4. Final Answer: 3.22 kg ✅