This document contains notes from a mathematics lesson on addition, subtraction, and estimation. It includes rules for adding positive and negative numbers, examples of adding fractions and decimals, word problems involving floor levels on an elevator and estimating total costs. It also has examples of evaluating expressions with variables and filling in comparison symbols.

1. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Warm­up
U
A B
1 7
2
5 8
4 3
6 C
A ∩ B =
A ∪ C =
B' =
B ∩ C =
Aug 23­8:15 AM
Chapter 1.4
Addition, Subtraction, and Estimation
Aug 23­8:14 AM
1

2. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Rules
The sum of 2 positive numbers is POSITIVE
The sum of 2 negative numbers is NEGATIVE
The sum of a negative and positive number will
have the same sign (+,­) as the number with the greater
absolute value
Adding numbers with different signs (+,­) is the same
as subtracting absolute values
Aug 23­8:20 AM
Examples:
4 + 4 = 8
(­4) + (­4) = ­8
(­6) + 4 = ­2
Aug 23­8:54 AM
2

3. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Adding Fractions
Need to have a common denominator
1
44 + 31
2
1 2
44 + 3 4
Aug 23­8:24 AM
Adding Decimals
4.1 + 6.3 =
(­6.8) + (­4.1) =
(­5.7) + 3.4 =
Aug 23­8:24 AM
3

4. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Example
(­23.6) + 19.7
Aug 23­8:30 AM
Example
Pretend you get on an elevator on the 4th floor of a building.
The elevator goes up 3 floors, down two, up five, then down three.
What floor do you end up on?
Aug 23­8:41 AM
4

5. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Estimation
The cost of mailing four packages is:
$4.86, $7.65, $2.12, $8.61
You have $25 in your wallet, is that enough?
Aug 23­8:40 AM
Example
Fill in the blank with < , > , or =
(­89) + (­77) _______ (­143) ­ (­35)
Aug 23­8:40 AM
5

6. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Example
Fill in the blank with < , > , or =
( ­4 3 ) + ( ­6 1 _______ (­18.0) ­ 6.75
4 2)
Aug 23­8:40 AM
Example
Evaluate the expression if
a = ­3
b = ­2
| (­a) ­ (a ­ b(a ­ b(a ­ b))) |
Aug 23­8:56 AM
6

7. Ch1.4_AdditionSubtractionEstimation.notebook August 23, 2011
Example
Evaluate the expression
5 x 6 + 12 ­ 4
Aug 23­9:03 AM
Page 22
2 ­ 58 evens
skip #28
Aug 23­9:05 AM
7