6th Grade Math Textbook, Fundamentals

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)

5. 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.