5-Minute Check 1) 5 x 7 2) 7 x 70 3) 9 x 20 4) 4 x 800 5) 6 x 8000 6) The each person to eat for one week is $200. Find the total cost for a family of.

5-Minute Check5-Minute Check1) 5 x 7

2) 7 x 70

3) 9 x 20

4) 4 x 800

5) 6 x 8000

6) The each person to eat for one week is $200. Find the total cost for a family of 5 to eat for one week.

1) 5 x 7

2) 7 x 70

3) 9 x 20

4) 4 x 800

5) 6 x 8000

6) The each person to eat for one week is $200. Find the total cost for a family of 5 to eat for one week.

Mental Math: Estimate Products

Mental Math: Estimate Products

ObjectiveObjective

By the end of this lesson, you will be able to estimate products by rounding factors and using easier numbers and then finding the product mentally.

Essential Question: What strategies can you use to multiply by a 1-digit number?

N.S. 1.3 - Round whole numbers through the millions to the nearest ten, hundred, thousand, ten thousand, or hundred thousand.

By the end of this lesson, you will be able to estimate products by rounding factors and using easier numbers and then finding the product mentally.

Essential Question: What strategies can you use to multiply by a 1-digit number?

N.S. 1.3 - Round whole numbers through the millions to the nearest ten, hundred, thousand, ten thousand, or hundred thousand.

ExploreExplore

What is a reasonable estimate for 6 x 22? Talk with your table to find an estimate

for 6 x 22. Think about what you have learned yesterday about multiplying by ten.

What is a reasonable estimate for 6 x 22? Talk with your table to find an estimate

for 6 x 22. Think about what you have learned yesterday about multiplying by ten.

ExplainExplain

Anyone willing to share their strategies?

Do you think the exact answer for 6 x 22 is greater or less than your estimate? Why?

Explain why finding an estimated answer is sometimes better than finding an exact answer.

Anyone willing to share their strategies?

Do you think the exact answer for 6 x 22 is greater or less than your estimate? Why?

Explain why finding an estimated answer is sometimes better than finding an exact answer.

More ExamplesMore Examples

Try these problems: 3 x 38 5 x 78 7 x 42

Try these problems: 3 x 38 5 x 78 7 x 42

ProblemProblem An African elephant is the largest living land

mammal. It uses its trunk to pick up objects that weigh up to three times as much as a 175-pound person. About how much weight can an African elephant pick up with its trunk?

Step 1 - Round the greater factor to the nearest hundred.

3 x 175 3 x 200 Step 2 - use mental math. 3 x 2 = 6 (basic fact) 3 x 20 = 60 3 x 200 = 600

An African elephant is the largest living land mammal. It uses its trunk to pick up objects that weigh up to three times as much as a 175-pound person. About how much weight can an African elephant pick up with its trunk?

Step 1 - Round the greater factor to the nearest hundred.

3 x 175 3 x 200 Step 2 - use mental math. 3 x 2 = 6 (basic fact) 3 x 20 = 60 3 x 200 = 600

Another ProblemAnother Problem

In one day, an African elephant eats 9 bags of food. Each bag weighs 57 pounds. How many pounds of food does the elephant eat?

9 x 57Use mental math.9 x 6 = 54 (basic fact)9 x 60 = 540

In one day, an African elephant eats 9 bags of food. Each bag weighs 57 pounds. How many pounds of food does the elephant eat?

9 x 57Use mental math.9 x 6 = 54 (basic fact)9 x 60 = 540

5 x 7,441 7 x $6.68 9 x 820 4 x 32 7 x 98

5 x 7,441 7 x $6.68 9 x 820 4 x 32 7 x 98

3 x 415 6 x $3.25 9 x 6,221 6 x 281 4 x 2,509

3 x 415 6 x $3.25 9 x 6,221 6 x 281 4 x 2,509

AssignmentAssignment

Blue Group – Blue PageEveryone else – page 270 - #’s 9-

25Get them all correct - no Math

homework

Blue Group – Blue PageEveryone else – page 270 - #’s 9-

25Get them all correct - no Math

homework