1. Rounding Natural Numbers and Multiplying 3-Digit Numbers by 2-Digit Numbers

2. Learning Goals
Students will learn to round natural numbers so that they can approximate the result of given equations.
Students will use their knowledge of multiplying 1-digit numbers so that they can multiply 3-digit numbers by 2-digit numbers.

3. Vocabulary Approximate Value Equation Factor Multiplication Multiply
Product
Rounding

4. Rounding Natural Numbers
When you round a number, you replace it with one of approximate value
Rounding numbers helps you estimate operations and makes mental calculation easier

5. Rounding 542 329 to the Nearest Thousand
Step
Example
1. Circle the digit in the position to which the number will be rounded.
2. Look at the digit to the right of the circled digit.
-If less than 5, the digit to be rounded
does not change
-If greater than or equal to 5, the digit
is rounded by 1
3. Replace all the digits to the right of the circled digit with 0
is closer to than to

6. Let’s Round Some Numbers
(nearest Th)
(nearest TTh)
(nearest T)
186 (nearest H)
5 173 (nearest Th)
20 000
200
5 000

7. Individual Work The reference page in your workbook is A-12
Take 5 minutes to complete:
Question #1 on page A-12
Question #2 on page A-13
Question #3 on page A-13
Question #4 on page A-13

8. Multiplying 3-Digit Numbers by 2-Digit Numbers
Understanding a multiplication question:
829 x 74 =
1st Factor multiplied by 2nd Factor equals the Product

9. Multiplying 3-Digit Numbers by 2-Digit Numbers
Multiply each digit in the number 829 by 4 (units). Don’t forget to carry! 1 3 Th H T U 8 2 9 7 4 6 x

10. Multiplying 3-Digit Numbers by 2-Digit Numbers
Place a 0 in the units column.
Multiply each digit in the number 829 by 7 (tens). 2 6
TTh Th H T U 8 9 7 4 3 1 5 x

11. Multiplying 3-Digit Numbers by 2-Digit Numbers
Add the 2 products to find the final product of the multiplication 2 6
TTh Th H T U 8 9 7 4 3 1 5 x +

12. Individual Work The reference page in your workbook is page A-14
Take 5 minutes to complete:
Question #1 on page A-15
Question #2 on page A-15
Question #3 on page A-16

13. Put It All Together Complete questions 1 and 2 on page A-17
Supplementary Activity 1-4