मुद्रा
Money
Money is the context in which primary children meet decimals, addition with carrying, subtraction with borrowing and the idea of change. The Indian rupee has 100 paise, so every money calculation is a two-decimal-place calculation in disguise.
Writing and converting
1 rupee = 100 paise | Rs 12.75 = 12 rupees and 75 paise
- Always write two digits after the decimal point in money: Rs 5.50, not Rs 5.5.
- To convert rupees to paise, multiply by 100. Rs 3.25 = 325 paise.
- To convert paise to rupees, divide by 100. 480 paise = Rs 4.80.
- Notes and coins currently in use: coins of 1, 2, 5, 10 and 20 rupees, and notes of 10, 20, 50, 100, 200 and 500 rupees.
The three question types
| Type | Example |
|---|---|
| Total cost | 3 pens at Rs 12.50 each cost Rs 37.50 |
| Change | Paid Rs 100 for goods worth Rs 68.25; change is Rs 31.75 |
| Comparison and best buy | 500 g at Rs 45 or 1 kg at Rs 85 - which is cheaper per kilogram? |
Profit, loss and simple interest
Profit = SP - CP | Loss = CP - SP | Profit % = (Profit / CP) x 100
Percentage of profit or loss is always calculated on the cost price, never on the selling price. Simple interest, which appears in Class 5 in some states, is calculated as principal multiplied by rate multiplied by time, divided by 100.
Unitary method
Most money problems in Classes 4 and 5 are solved by the unitary method: find the value of one, then multiply. If 6 notebooks cost Rs 234, one costs Rs 39, so 8 cost Rs 312. The same two steps handle rate, speed and best-buy comparisons, which is why the method is worth naming explicitly rather than leaving it as an unspoken habit.
Why money is good teaching material
- It is real, so children are already motivated and already competent with it outside school.
- It makes decimals concrete: a paisa is visibly one hundredth of a rupee.
- Shop role play in the classroom lets a child practise addition, subtraction and estimation at once.
- It reaches first-generation learners who handle money at home daily but freeze at a written sum.
✗ Profit percentage is calculated on the selling price. | ✓ It is calculated on the cost price.
संकेत: 1 रुपया = 100 पैसे; लाभ या हानि का प्रतिशत हमेशा क्रय मूल्य (cost price) पर निकाला जाता है।
Money gives about one question, usually a word problem combining multiplication and subtraction for change. The consistent trap is the base of the profit percentage — always the cost price. A pedagogy version of this topic also appears, asking why shop role play is a good method; the answer connects real context, motivation and the concrete meaning of decimals. Watch the two-decimal convention, since options sometimes differ only in the way the amount is written.
Frequently asked questions
How do you convert rupees into paise?
Multiply the amount in rupees by 100, since one rupee equals one hundred paise. So Rs 3.25 becomes 325 paise, and conversely 480 paise becomes Rs 4.80 when divided by 100.
Is profit percentage calculated on cost price or selling price?
On the cost price. Profit equals selling price minus cost price, and the percentage is that profit divided by the cost price, multiplied by one hundred.
Why is money a good context for teaching decimals?
Because a paisa is physically one hundredth of a rupee, so decimal place value becomes concrete. Children also handle money outside school, which gives them existing competence and motivation to build on.
60-second recap
- 1 rupee = 100 paise; money is always written with two decimal places.
- Question types: total cost, change, and comparison or best buy.
- Profit = SP - CP; loss = CP - SP; percentage always on cost price.
- Simple interest = principal x rate x time divided by 100.
- Shop role play teaches decimals, operations and estimation together.