Unit 8 · Topic 01 · Money and Time
Anaya ran the class store for the day: pencils ₹8, erasers ₹5, sharpeners ₹12.
Kabir bought two pencils, one eraser, and handed over a ₹50 note.
The whole till depended on Anaya doing three sums in the right order, correctly.
For Maths Week, Ms. Rao set up a pretend classroom shop. Anaya was the shopkeeper. Prices: pencil ₹8, eraser ₹5, sharpener ₹12, notebook ₹35.
Kabir walked up. "Two pencils and one eraser, please." He handed over a ₹50 note.
Anaya worked the bill step by step. First, the cost of each item: 2 pencils at ₹8 each is 2 × 8 = ₹16. One eraser is ₹5. "Now I add them together: 16 + 5 = ₹21. That's your total."
"And my change?" asked Kabir.
"You paid ₹50, the bill is ₹21. 50 minus 21 is ₹29 change." Anaya counted it out: one ₹20 note, one ₹5 note, two ₹2 coins — 20 + 5 + 2 + 2 = 29. "Checks out."
Ms. Rao then sent up a harder customer: Anaya herself needed to buy 3 notebooks and 4 sharpeners from a real shopkeeper role played by Ms. Rao, paying with a ₹200 note.
"Break it into parts," said Ms. Rao. "3 notebooks at ₹35 each — work that out first." Anaya multiplied: 3 × 35 = ₹105.
"4 sharpeners at ₹12 each?" 4 × 12 = ₹48.
"Now add the two parts together for the full bill." 105 + 48 = ₹153.
"And the change from ₹200?" 200 − 153 = ₹47.
"Every money word problem breaks into the same three moves," said Ms. Rao. "Find the cost of each kind of item — usually a multiplication. Add all those costs together for the total bill. Then, if there's a payment involved, subtract the bill from what was paid, to find the change. Skip a step, or do them out of order, and the answer comes out wrong even if your arithmetic is perfect."
A money word problem almost always breaks into three steps: (1) multiply price × quantity for each kind of item, (2) add all those amounts together for the total bill, (3) subtract the bill from the amount paid to find the change.
Always work out cost-per-item-type BEFORE adding — adding raw prices without multiplying by quantity first gives a wrong total.
Change = amount paid − total bill. If the bill is more than what was paid, more money is owed, not change.
Rupees and paise work like whole numbers and decimals: ₹1 = 100 paise, so ₹8.50 means 8 rupees and 50 paise, added and subtracted the same way as any decimal.
Make a pretend price list for 4 items, then work out the bill for buying 2 of one item and 3 of another.
Pay a pretend ₹100 note for something costing ₹67 and work out the change.
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