Why GST matters for your maths exam
Ever wondered why a simple price tag suddenly shows extra numbers? That extra is GST – and it shows up in many maths problems.
GST (Goods and Services Tax) is a tax added to the price of almost everything you buy or sell. Think of it like a small extra charge that the government collects on each transaction.
What is GST in plain language?
GST stands for Goods and Services Tax. It’s a single tax that replaces many smaller taxes. The idea is simple: one tax, one rate, one system. The money goes to the government to build roads, schools, and hospitals.
How GST is split
Depending on where the sale happens, GST is divided into:
- CGST – Central GST, collected by the central government.
- SGST – State GST, collected by the state where the sale occurs.
- IGST – Integrated GST, used when goods move from one state to another.
Common GST rates for everyday items
| Category | GST Rate |
|---|---|
| Essential items (e.g., food grains) | 5% |
| Standard goods (e.g., clothes) | 12% |
| Most consumer goods (e.g., electronics) | 18% |
| Luxury items (e.g., cars) | 28% |
How to calculate GST – step by step
Think of GST like adding a splash of sauce to a plain dish. You start with the base price, then sprinkle the right amount of tax.
- Identify the taxable (base) value of the product or service.
- Find the applicable GST rate from the table above.
- Calculate the GST amount: GST = Base Value × (Rate ÷ 100).
- Add the GST amount to the base value to get the final invoice price.
Solved example 1: Buying a television
Rohit wants to buy a TV priced at Rs. 20,000. The TV falls under the 18% GST slab.
Step 1: Base value = Rs. 20,000.
Step 2: GST rate = 18%.
Step 3: GST amount = 20,000 × (18 ÷ 100) = 20,000 × 0.18 = Rs. 3,600.
Step 4: Final price = 20,000 + 3,600 = Rs. 23,600.
So Rohit pays Rs. 23,600 in total. If we break the 18% into CGST and SGST, each is 9%, so CGST = Rs. 1,800 and SGST = Rs. 1,800.
Solved example 2: Selling a design service across states
Alice, a freelance designer in Maharashtra, charges a client in Karnataka Rs. 10,000 for a logo. Since it’s an inter‑state sale, IGST applies at 12%.
Step 1: Base value = Rs. 10,000.
Step 2: GST rate = 12% (IGST).
Step 3: GST amount = 10,000 × 0.12 = Rs. 1,200.
Step 4: Final invoice = 10,000 + 1,200 = Rs. 11,200.
Alice will remit the entire Rs. 1,200 to the central government as IGST.
Quick cheat‑sheet
- Identify base price.
- Pick the right GST slab (5, 12, 18, 28%).
- Use the formula: GST = Base × Rate ÷ 100.
- Add GST to base for final amount.
- Split into CGST+SGST for intra‑state, IGST for inter‑state.
📝 Likely Exam Questions
- Calculate the GST amount and final price for a fridge costing Rs. 15,000 with a GST rate of 18%.
Answer: GST = 15,000 × 0.18 = Rs. 2,700; Final price = Rs. 17,700. - A shop sells a pair of shoes for Rs. 2,200 inclusive of 12% GST. Find the base price and the GST amount.
Answer: Base = 2,200 ÷ 1.12 = Rs. 1,964.29; GST = 2,200 – 1,964.29 = Rs. 235.71. - Explain the difference between CGST, SGST, and IGST with an example each.
Answer: CGST & SGST are levied on intra‑state sales; e.g., a Delhi shop selling a book to a Delhi customer (9% CGST + 9% SGST). IGST is for inter‑state sales; e.g., a Mumbai vendor selling software to a Chennai buyer (18% IGST). - If a service worth Rs. 8,000 attracts 5% GST, what will be the amount shown on the invoice?
Answer: GST = 8,000 × 0.05 = Rs. 400; Invoice total = Rs. 8,400.