6th Grade Math Textbook, Fundamentals

(Marvins-Underground-K-12) #1
Lesson 4-5 for exercise sets. &KDSWHU 

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Subtract:  6 2.08
 6 (2.08)

Estimate using rounding:  6 (2)  8
Then add:  6 (2.08)
6.00
(2.08)
8.08

So  6 2.08 8.08

Check:The estimate of 8 is close to
8.08, so the answer is reasonable.

Subtraction
Principle

Both addends are negative,
so the sum is negative.

2 Subtract: 12.4 (0.009)
12.4 0.009 Subtraction Principle


Estimate using rounding: 12  0  12
Then add: 12.4 0.009
12.400
0.009
12.409

So 12.4 (0.009) 12.409.

Check:The estimate of 12 is close to 12.409,
so the answer is reasonable.

Both addends are positive,
so the sum is positive.

3

Find the sum or difference.
1.11.7 3.3458 2.0.7 (2) 3. 7 6.1 4.5.8 (3.07)


  1. 8 0.0909 6.0.0123 (4.1) 7.2.4 (5.6) 8.3.992 7.08


9.Evaluate abcwhen a4.035, b17, and c12.3.

10.Discuss and Write For a3.2, b7.1, and c4.5, which is
greater: abcor abc? Explain your answer.

To add more than two rational numbers, follow the rules for the order

of operations, and apply appropriate properties to evaluate the expression.

Evaluate abc whena 3.5, b8.1, and c3.5.
3.5 8.1 3.5 Substitute 3.5 for a, 8.1 for b, and 3.5 for c.
3.5 3.5 8.1 Use the Commutative Property of Addition.
(3.5 3.5)8.1 Use the Associative and the Inverse Properties of Addition.
0 8.1 Use the Identity Property of Addition.
8.1

Subtract: 2.03 (5.7)
First estimate by rounding:  2 (6)  2  6  4
Then add: 2.03 5.7

3.67 is close to the estimate of 4, so the answer is reasonable.
So 2.03 (5.7) 3.67.

2.03
 5.70

5.70
2.03
3.67

|5.70|
|2.03|

2.03
(5.70)

1

|5.7|is greater
than |2.03|, so the
result is positive.

Subtract the lesser
absolute value from the
Add the opposite of thenumber being subtracted. greater absolute value.
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