Money Math · Lesson Plan
Multiplying Decimals to Calculate Costs
Money is written in decimals, so calculating costs means multiplying decimals. This lesson reviews how to multiply a decimal by a whole number and applies it to real-life cost problems — like finding the total for several items at a given price.
For Teachers
Lesson at a glance
- Topic
- Money Math
- Grade Level
- Grades 6–9
- Resource Type
- Lesson + Worksheet
- Estimated Time
- 30–45 minutes
- Format
- Reading + practice worksheet
- Materials
- Printable lesson, worksheet, calculators
What Students Learn
Learning objectives
- Review how to multiply a decimal by a whole number
- Explain how money amounts are written as decimals
- Apply decimal multiplication to real-life cost problems
- Place the decimal point correctly in a product
- Check that a calculated cost is reasonable
Materials
What you’ll need
- Printed copies of the lesson and worksheet (one per student)
- Calculators
- Whiteboard or projector for worked examples
Key Terms
Vocabulary
- Decimal
- A number with a fractional part written after a point, like $3.45.
- Whole number
- A number with no fractional part.
- Product
- The result of multiplying.
- Decimal point
- The dot separating whole dollars from cents.
- Unit price
- The cost of a single item.
- Total cost
- The full amount for all items.
For Teachers
Lesson plan
Estimated time: one 30–45 minute class period.
Lesson sequence
- Warm-up (5 min). Review that $3.45 means 3 dollars and 45 cents, and how to multiply ignoring the decimal first.
- Read the method (10 min). Students read how to multiply a decimal by a whole number and place the decimal point.
- Worked example (10 min). Find the total cost of several items at a given price.
- Worksheet (12 min). Students practice; the answer key is included for teacher use.
Assessment
Assess the worked example and worksheet practice.
Discussion
Discussion questions
- Why are money amounts written using decimals?
- How do you multiply a decimal by a whole number?
- How do you know where to place the decimal point in the answer?
- How would you find the total cost of buying several of the same item?
- How can you estimate to check that your answer is reasonable?
Printable Lesson & Worksheet
Multiplying Decimals to Calculate Costs — Lesson & Worksheet
Printable lesson plus practice problems, with an answer key for teacher use.
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