← The Course Notes
STILLWATER CROSSING · THE COURSE NOTES · BRIDGE MATH 5/6

Week 29 · Multiplying Decimals

This week
Lessons 136, 137, 138, 139 & 140
Papers
Test 14 to do at home
Method
No calculators, ever · show every step
Instructional notes

Multiplying a Decimal by a Decimal

To multiply decimals: • Multiply as usual • Count total decimal places in both factors • Place the decimal point in product

Example

Multiply.

worked example from the course notes
Practice

Multiply.

1.1 × 7.7 = 8.47 0.25 × 4.7 = 1.175

1.05 × 0.25 = 0.2625 7 × 1.5 = 10.5

Decimal and Fraction Review

worked example from the course notes
worked example from the course notes
worked example from the course notes

1.706

✍ In your own words

explain, why do we count decimal places in the factors and then place the decimal in the product when multiplying decimals? What would happen if we forgot this step? Suggested answer: The standard rule of counting and adding decimal places works because when we remove decimals to multiply, we are secretly multiplying our numbers by powers of 10. To fix this, we must divide our final whole-number answer by those same powers of 10.

Homework this week
Work-textLesson 136Lesson 137Lesson 138Lesson 139Lesson 140
Speed drill136137138140

Terms on the record

TermMeaning
multiplying decimalsMultiplying a Decimal by a Decimal
STILLWATER CROSSING // BRIDGE MATH // PENUMBRA · steady on