Unit 5, Lesson 21
Multiply More Decimals
Grade 5
Warm-up
Central Park is a large park in Manhattan. It is about 3.85 kilometers long and 0.79 kilometer wide. What is the approximate area of Central Park?
Record an estimate that is:
| too low | about right | too high |
|---|---|---|
Student Section Summary
We learned different strategies for multiplying with decimals.
We used place value relationships to reason about the multiplication.
Example: because 6 groups of 14 hundredths is or 84 hundredths.
We used properties of operations to break up the multiplication.
Example:
We also used diagrams to represent the multiplication.
Example: This diagram shows 17 groups of 3 hundredths is 51 hundredths, so .
Two diagrams. Each squares. Length and width, 1. Each partitioned into 10 rows of 10 of the same size squares. On left, 30 squares shaded. On right, 21 squares shaded.