1. Using Compatible Numbers to Estimate
Lesson 7-4
CCSS 4.NBT.5, 4.NBT.3, 4.OA.3
Literature Link: The Grapes of Math by Greg Tang (1-2 pages of riddles)

2. MATH Essential Questions
How can greater products be found mentally?
MATH
Essential
Questions

3. MATH Essential Questions
How can greater products be estimated?
MATH
Essential
Questions

4. Warm Up
Write the multiplication and division fact family for these numbers. 6, 9, 54

5. Let’s look at the Envision Video for this lesson and take the quiz.
Today’s Lesson
In this lesson, you will use both compatible numbers and rounding to estimate solutions to multiplication problems with two 2-digit numbers.
Let’s look at the Envision Video for this lesson and take the quiz.

6. Think and Write
Who are some people you get along very well with? People whom we get along well with and enjoy being around are people whom we are compatible with.

7. 30 is close to 31, so they are compatible.
Compatible Numbers
Compatible numbers are numbers that are close to the actual number, but easier to compute mentally.
Example: 25 is close to 24, and is easy to compute with. It is a compatible number.
30 is close to 31, so they are compatible.

8. Think About It: Why is it easy to multiply with 25?
Estimate 24 x 41
Rounding to the nearest ten gives 20 x 40 = 800 as an estimate.
However, you can get a closer estimate by using compatible numbers which are numbers that are easy to compute mentally.
24 is close to 25.
41 is close to 40.
25 and 40 are compatible numbers.
25 x 4 = 100 so 25 x 40 = 1,000.
Think About It: Why is it easy to multiply with 25?

9. Practice!
Estimate to find the product. When possible, use compatible numbers. Look for numbers near 25.
26 X 42
22 X 26
64 X 24
89 X 43
53 X 54

10. Problem 1
Sean has 19 Lego sets. Each set has 96 pieces. How many pieces are there in all? Estimate using compatible numbers and solve.

11. Problem 2
Danielle is making necklaces for 16 friends. Each necklace has 44 beads. How many beads will Danielle use in all? Estimate using compatible numbers and solve.

12. Problem 3
Jack is apple picking. He picks 21 apples a minute. If he picks for 34 minutes, how many apples will Jack pick? Use compatible numbers to estimate and solve.

13. Problem 4
Isabel is slicing 24 cakes. She slices each cake into 16 pieces. How many pieces does Isabel slice in all? Estimate using compatible numbers and solve.

14. Lesson Wrap Up
In this lesson, you learned use compatible numbers as another way to estimate solutions to multiplication problems.
Reflection in Notebook: I would explain compatible numbers to a friend by….
Center Activity – Toss and Talk (7-4).
Homework (7-4 Practice) for one “Paw Signature” and (7-4 Reaching & Practice) if you want two “Paw Signatures.”
Website for Practice: mes.php