Chapter 6, The Dairy Farm, is about multiplication shortcuts that make big calculations fast: doubling and halving, multiplying by 10, 100 and 1000, and splitting numbers into friendly parts before multiplying. These extra questions use everyday dairy-farm numbers to practise them.
Practice Questions
Q1. A dairy farm sells 25 litres of milk every day. How many litres does it sell in 10 days? Use the ×10 shortcut.
Multiplying by 10 just adds one zero: 25 × 10 = 250 litres.
Q2. A milk crate holds 48 bottles. Double this to find how many bottles are in 2 crates, then double again for 4 crates.
Doubling 48 gives 96 bottles (2 crates); doubling 96 gives 192 bottles (4 crates).
Q3. One cattle feed bag costs ₹150. Find the cost of 100 bags using the ×100 shortcut.
150 × 100 = 15,000 (attach two zeros), so 100 bags cost ₹15,000.
Q4. Complete this friendly-parts multiplication: 36 × 5 = (30 × 5) + (6 × 5).
30 × 5 = 150 and 6 × 5 = 30, so 36 × 5 = 150 + 30 = 180.
Q5. Halving is the opposite of doubling. If a farm’s daily milk output of 84 litres is shared equally between 2 tankers, how much goes in each?
Half of 84 is 42 litres per tanker.
Why These Help
Farmers, shopkeepers and delivery workers deal with bulk quantities every day — crates of bottles, sacks of feed, cans of milk. Doubling, halving and multiplying by powers of 10 let you work these out in your head instead of writing long multiplication every time, which builds both speed and number confidence.
Frequently Asked Questions
Q. Why is multiplying by 10, 100 or 1000 so quick?
Because in our place-value system, each extra zero shifts every digit one place to the left, so we simply attach the zeros instead of doing repeated addition.
See the Chapter 6 Solutions and Revision Notes for the full walkthrough.
