Decimal Multiplication Extension

Name:

Date:

Calculator and decimal numbers illustration

🎯 WALT: Solve complex decimal multiplication problems in real-world contexts

Success Criteria:

I can multiply decimals greater than 1 and less than 1
I can solve multi-step problems involving money and measurements
I can recognise patterns when multiplying by 0.1 and 0.01

💰 Part 1: Budgeting and Money Problems

1. Sarah is planning a school fundraiser. She needs to buy 12.5 kg of chocolate at $8.40 per kilogram. She also needs 15.75 metres of ribbon at $2.60 per metre. Calculate the total cost and show your working.

2. A family restaurant uses 4.8 kg of flour per day. If flour costs $1.35 per kilogram, how much will they spend on flour in 2.5 weeks? (Remember: 1 week = 7 days)

3. Tom saves $12.75 each week. If he continues saving at this rate for 1.6 years, how much will he have saved? (Use 1 year = 52 weeks)

🍳 Part 2: Recipe Adjustments and Patterns

4. A cake recipe serves 8 people and calls for 2.25 cups of flour. If you want to make the recipe for 14 people, how much flour will you need? Show your calculation steps clearly.

5. Pattern Investigation: Complete the following multiplication patterns and explain what you notice.

a) 45.6 × 1 = _______

b) 45.6 × 0.1 = _______

c) 45.6 × 0.01 = _______

d) 45.6 × 0.001 = _______

What pattern do you notice when multiplying by 0.1, 0.01, and 0.001?

6. A rectangular garden measures 8.4 metres by 6.75 metres. Calculate the area in square metres. Then calculate how much it would cost to cover this area with mulch that costs $3.20 per square metre.

7. Challenge Problem: A car travels at an average speed of 67.5 kilometres per hour. How far will it travel in 2.4 hours? If petrol costs $2.35 per litre and the car uses 8.2 litres per 100 kilometres, what is the total cost of petrol for this journey?

8. Reflection: Choose one problem from above and write step-by-step instructions explaining how someone else could solve it.