📖 NOTES
Class 5
Chapter 8: Weight and Capacity
Math Mela · Quick Revision Notes
Class 5Math Mela (NCERT)Chapter 8
📚 What's in this Chapter
⚖️ Reading Weighing Scales
Dial (analog) scales have a pointer that moves as weight is added. The "0" mark shows empty, and the pointer moves clockwise as weight increases.
🌟 Always check what the MAXIMUM value on the dial is (like 1kg, 2kg, 4kg, or 6kg) — this tells you the value of each small tick mark between the numbers!
💡 Common-sense check: an iron almirah weighing "40 g" doesn't make sense — that's lighter than a few coins! It should be around 40 kg. Always ask: "does this weight make sense for the object?"
📏 Units of Weight — kg, g, mg
1,000 mg = 1 g | 1,000 g = 1 kg
| Convert | Method | Example |
|---|---|---|
| kg → g | × 1,000 | 3 kg 500 g = 3,500 g |
| g → kg | ÷ 1,000 | 4,080 g = 4 kg 80 g |
| g → mg | × 1,000 | 4 g 100 mg = 4,100 mg |
⚠️ Careful with "extra" grams!
"5 kg 50 g" means 5,000g + 50g = 5,050 g — NOT 5,500g! The "50" is just 50 grams, not "50" meaning "500."🐜 Milligram (mg)
Used for VERY light things — like ants (1-5 mg), medicine doses, or gold ornaments.🏋️ Quintal & Tonne (for VERY heavy things)
100 kg = 1 Quintal | 10 Quintals = 1 Tonne | 1,000 kg = 1 Tonne
These bigger units are used for things like truckloads of grain, or a vehicle's weight!
➕➖ Adding & Subtracting Weights
Just like with length, add/subtract the kg parts and g parts separately, regrouping when the grams cross 1,000:
2 kg 500 g + 1 kg 750 g = 3 kg + 1,250 g = 4 kg 250 g
💡 For subtraction, if the grams on top are smaller, "borrow" 1,000g from the kg column — just like borrowing 10 in normal subtraction!
✖️➗ Multiplying & Dividing Weights
4 × (10 kg 500 g) = 40 kg + 2,000 g = 40 kg + 2 kg = 42 kg
(4 kg 800 g) ÷ 4 = 1 kg 200 g (divide kg and g parts separately)
🥤 Capacity — Litres & Millilitres
1,000 ml = 1 litre (l)
| Convert | Method |
|---|---|
| l → ml | × 1,000 |
| ml → l | ÷ 1,000 |
Add/subtract/multiply/divide capacities exactly the same way as weights — just replace kg↔l and g↔ml!
📝 Chapter Summary
- 1000mg=1g, 1000g=1kg, 100kg=1quintal, 10quintal=1tonne(1000kg)
- 1000ml=1litre
- Add/subtract like units (kg with kg, g with g), regrouping at 1,000
- Multiply/divide by handling the kg and g/ml parts separately, or convert fully first
- Always sanity-check: does the weight/capacity make sense for the real object?