5-Minute Check Multiply. 2 x 44 4 x 39 3 x $21 5 x 89 A truck weighs twice as heavy as a car. The...

5-Minute Check•Multiply.

•2 x 44

•4 x 39

•3 x $21

•5 x 89

•A truck weighs twice as heavy as a car. The car weighs 3,000 pounds. How much does the truck weigh?

Multiply Multi-Digit Numbers (even across zeros)

ObjectiveBy the end of the lesson, you will be

able to multiply a three-digit and a four-digit number by a one-digit number.

Standard 4NS3.2 - Demonstrate an understanding of, and the ability to use, standard algorithms for multiplying a multidigit number by a two-digit number and for dividing a multidigit number by a one-digit number; use relationships between them to simplify computations and to check results.

Introduce Let’s look at a problem: 1, 124

x3

• How many ones are in 1,124?

• Multiply the ones by the 3. What is the product? Should we carry over?

• Multiply the tens. What is the product? Should we carry over any?

• Multiply the hundreds. What is the product? Should we carry over?

• Multiply the thousands. What is the product?

• What is the final answer?

Example• Today is Anna’s birthday, and she is nine years

old. There are 365 days in one year. How many days old is Anna?

• You multiply multi-digit numbers the same way you multiply a two-digit number by a one-digit number.

• 365

x9

First, multiply the 9 by 5. Anything to carry over?

Next, multiply the 9 by the 6 (tens) and add the carried-over amount. Anything to carry over?

Then, multiply the 9 by the 3 (hundreds) and add the carried-over amount.

LET”S LISTEN!!•Let’s hear from Mrs. Verughese about multiplying money using four-digit by one-digit.

•Mrs. Verughese!!

•Let’s listen to Mr. Parsons as he explains another problem with a zero as one of the digits.

•Mr. Parsons!!

Teach• Let’s look at a problem that has a zero in it:

• 1,104

x3

• How many ones are in 1,104? Multiply the ones by 3. What is the product? Anything to carry over?

• How many tens are in 1,104? What is the product of any number and zero? Then, add the carried over amount. Anything to carry over?

• Multiply the hundreds. What is the product? Anything to carry over?

• Multiply the thousands. What is the product? Add the carried over amount.

Bales Bucks

Multiply. Check for reasonableness by estimating the products.

303 x 3

$507 x 6

908 x 8

2,007 x 8

8 x 47

Multiply. Check for reasonableness.

135 x 2

532 x 6

$2,957 x 3

7,832 x 7

Assignment

Page 280 - #’s 7 – 12

Page 286 - #’s 9 - 15

Get them all correct – No Math Homework