Addition of Whole Numbers and Decimals

1
Addition of Whole Numbers and Decimals

• Lesson 2-2

2
Objectives

• To review place value concepts and the use of
  partial-sums and column addition.
• Write numbers in expanded notation

3
Mental Math

• Expanded form means taking numbers apart by their
  place value.
• For example 25 would be 20 5, taking the tens
  and the ones apart.
• Another example 0.351 would be
• 0.3 0.05 0.001

4
Mental Math Write the following numbers in
expanded form. Number your piece of paper 1 - 8

• 0.52 0.5 0.02
• 52 50 2
• 0.35 0.3 0.05
• 35 30 5
• 467 400 60 7
• 0.241 0.2 0.04 0.001
• 241 200 40 1
• 162 100 60 2

5
Math Message

• You need your SRB Student Reference Book.
• Turn to page 28 30.
• Use these pages to answer the Check Your
  Understanding Problems on the bottom of page 30.
• As you work, think about one true statement that
  could be made about the base-ten system for
  numbers.

6
Now that youve read the SRB

• Look at the place value chart on page 30 of your
  SRB.
• Look over the headings on the chart.
• Describe any patterns you see.

7
Here are some patterns you might have noticed

• The numbers decrease in size from left to right.
• The columns on the right side of the chart have a
  decimal point and the left side does not.
• The zeros 0s increase by one for each column as
  you move outward from the center in either
  direction.

8
Math Message Follow Up

• Each place has a value that is 10 times the value
  of the place to its right.
• For example, 1,000 is 10 times as much as 100
• 100 is 10 times as much as 10
• 10 is 10 times as much as 1
• 1 is 10 times as much as 0.1
• 0.1 is 10 times as much as 0.01

9
Check out how the numbers line up.

• 0.01 x 10 0.1
• 0.1 x 10 1.0
• 1.0 x 10 10.0
• 10 x 10 100.0
• 100 x 10 1,000.0

10
Whats the opposite of multiplication?

• Division of course.
• Each place has a value that is one-tenth the
  value of the place to its LEFT.
• For example
• 100 is 1/10 of 1,000
• 10 is 1/10 of 100
• 1 is 1/10 of 10
• 0.1 is 1/10 of 1
• 0.01 is 1/10 of 0.1

11
Division of numbers by 10s

• 0.01 x 10 0.1
• 0.1 x 10 1.0
• 1.0 x 10 10.0
• 10 x 10 100.0
• 100 is 1/10 1,000.0