6th Grade Math Textbook, Progress

“is approximately equal to”

Write the

decimal point.

Subtract. Regroup

if necessary.

Line up the

decimal points.

Update your skills. See page 6.

Subtraction of Whole Numbers and Decimals

1-8

The Panama Canal is 81.6 km long

and the Suez Canal is 175.5 km long.

How much longer than the Panama

Canal is the Suez Canal?

First estimate by rounding.

180 
 80  100

Then to find how much longer,

subtract: 175.5
81.6

0 17 4 15 0 17 4 15

1 7 5. 5 1 7 5.5 1 7 5.5


 0 8 1. 6 
 0 8 1.6 
 0 8 1.6

 0 9 3 9  0 9 3. 9

So the Suez Canal is 93.9 km

longer than the Panama Canal.

Study these examples.

8,309,000
777,625 3 
0.7185

Add to check: Add to check:

7,531,375 777,625 8,309,000 2.2815 0.7185 3.0

The answer is reasonable. The answer is reasonable.

??

?

93.9
 100

The answer is reasonable.

12 9 9

7 2 10 8 10 10 10


8,3 0 9, 0 0 0


8,7 7 7 , 6 2 5


7,5 3 1, 3 7 5

9 9 9

2 10 10 10 10


3.0 0 0 0


 8 0.7 1 8 5


2.2 8 1 5

3 3.0000

2.0

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