NOTE: This review doesn’t include the ratio, proportions and %....use the sample test and all your notes from class for this!

Comparing and Ordering Decimals

Order the decimals from least to greatest.

16.67, 16.6, 16.0716.67

16.60

Compare two of the numbers at a time.

Write 16.6 as “16.60.”16.60 < 16.6716.67

16.07Start at the left and compare the digits.16.07 <

16.6716.60

16.07Look for the first place where the digits are different.

16.07 < 16.60

You can estimate a range for the sum by adjusting the decimal part of the numbers. Round the decimals to 0, 0.5, or 1.

0.86 1.00Add the decimal part of the numbers.

0.97 1.00 Add the whole-number estimate and the adjusted estimate. 0.40 + 0.50

2.50

48.00 + 2.50 = 50.50

The adjusted decimals are greater than the actual decimal, so 50.50 is an overestimate.

The estimated range for the sum is from 48.00 to 50.50.

Try This: Example 4

Estimate a for the sum.

8.92 + 47.88 + 3.41

Use front-end estimation.

8.92 8 Add the whole numbers only.

47.88 47 The whole-number values of the decimals are less than the actual numbers, so the answer is an underestimate.

3.41 + 3

at least 58

The exact answer of 8.92 + 47.88 + 3.41 is 58 or greater.

To write the number 3,456,000 in scientific notation, do the following:

3,456,000Move the decimal point left to form a number that is greater than 1 and less than 10.

3,456,000 Multiply that number by a power of ten.

3.456 106

The power of 10 is 6, because the decimal point is moved 6 places left.

Write each number in scientific notation.

A. 8,000,000

B. 587,000

8,000,000 Move the decimal point 6 places left. The power of 10 is 6.

8,000,000 = 8 106

587,000 Move the decimal point 5 places left. The power of 10 is 5.

587,000 = 5.87 105

Write each number in standard form.

A. 6.2174 103

B. 9.5 108

The power of 10 is 3.

6.2174 103 = 6,217.4

6.2174

The power of 10 is 8.

9.50000000

Move the decimal point 3 places right.

Move the decimal point 8 places right. Use zeros as placeholders. 9.5 108 = 950,000,000

41. 4

+ . 35

Try this: 41.4 + .35 =

41 75

0

4. 1 4

+ 35

Try this: 4.14 + 35 =

39 1 4

00

.8

+ . 8

Try this: .8 + .8 =

1 6

0

0

4

- .3 5

Try this: 4 - .35 =

3 6 5

00

0

4 . 4

- .9 5

Try this: 4.4 - .95 =

3 4 5

0

0

3 5. 9

X . 4 2

Try This One!

7 1 8 1 4 3 6 01 5 0 7 8

2 . 7 6

X .0 3 2

Try This One!

5 5 2 8 2 8 0 08 8 3 2

8316 divided by 36

3 6 8 3 1 67 21 1

1

3

1 0 83 6

1

3 6

2

Remember Me!

8.316 divided by .36

3 6 8 3 1 67 21 1

1

3

1 0 83 6

1

3 6

2

831.6 divided by .36

3 6 8 3 1 67 21 1

1

3

1 0 83 6

1

3 6

200

3 divided by 5

5 33 000

60