GRADE 9 Mathematics MEASUREMENTS – MONEY Notes
Mathematics — Measurements: MONEY
Level: Kenyan grade ~14 years old (Form 2). These notes explain money as a measurement, using the Kenyan Shilling (KSh / KES) in simple steps with examples and short exercises.
1. What is money as a measurement?
Money measures value. In calculations we treat money like decimal numbers (units and subunits). The Kenyan currency is the Kenyan Shilling (symbol: KSh). One shilling is divided into 100 cents: 1 KSh = 100 cents.
2. Common Kenyan denominations
Typical currency you will see:
Banknotes commonly used: KSh 50, KSh 100, KSh 200, KSh 500 and KSh 1000.
3. Working with money (rules)
- Treat money as decimal numbers: KSh 48.50 means 48 shillings and 50 cents.
- Align the decimal points when adding or subtracting prices.
- Use highest denominations first when giving change (notes before coins).
4. Examples (worked)
John buys a notebook for KSh 48.50 and pens for KSh 23.75. What is the total?
23.75
----
72.25
A customer pays KSh 200 for goods costing KSh 134.75. Find the change.
A radio costs KSh 2,500. A shop gives 10% discount. New price?
New price = 2,500 − 250 = KSh 2,250
If VAT is 16% and an item costs KSh 500 (price before tax), total price = ?
Total = 500 + 80 = KSh 580
5. Currency exchange (simple conversion)
To convert foreign money to KSh: multiply foreign amount by the exchange rate (KSh per foreign unit). Example: if 1 USD = KSh 140, then
To convert KSh to USD: divide by the rate. KSh 2800 ÷ 140 = USD 20.
6. Tips for calculations
- Write numbers in columns and align decimal points.
- Check by estimating: approximate sums in whole shillings to see if answer is reasonable.
- When handling percentages, work out the percent as a decimal (eg. 16% = 0.16).
- Use a calculator for large sums, but know the steps by hand.
7. Practice questions
- Mary buys fruit for KSh 76.40 and a drink for KSh 22.60. She pays with KSh 200. How much change should she get?
- An item is marked KSh 1,200. There is a 15% discount. What is the discounted price?
- Convert KSh 7,000 to USD if 1 USD = KSh 140.
- A shopkeeper sold 3 pens at KSh 45.50 each and 2 notebooks at KSh 78.25 each. Find total sales.
8. Answers
- Total = 76.40 + 22.60 = KSh 99.00. Change = 200 − 99 = KSh 101.00.
- Discount = 15% of 1,200 = 0.15×1,200 = 180. Price = 1,200 − 180 = KSh 1,020.
- 7,000 ÷ 140 = USD 50.
- Pens: 3×45.50 = 136.50. Notebooks: 2×78.25 = 156.50. Total = 136.50 + 156.50 = KSh 293.00.
Note: exchange rates and coin usage change over time — always use the current rates and available denominations in real transactions.