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Math Coach Amy
Amy Ferguson Moncure

7th Grade Math · Unit 2

Scientific Notation,
Negative Powers

Negative powers of 10. Swoop the decimal point to the left, and fill empty places with zeros.

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What to Remember

digit . stuff × 10 to the swoops

Draw a short line for the digit. Then a decimal point. Then a longer line for the other digits. Then × 10 to the number of swoops.

digit
.
 
stuff
× 10
# of swoops

Negative exponents swoop left

The exponent is the number of swoops. Swoop the decimal point to the left that many times.

Fill each empty place with a zero.

The number is small and positive. A negative exponent does not make a negative number.

Back to scientific notation

A small number already shows its decimal point.

Swoop right until one digit is in front of the decimal point.

The number of swoops is the exponent, and the exponent is negative.

Easy

Standard Form

Negative powers of 10. Swoop left. Problems 1–10 have an integer coefficient. Problems 11–20 have a decimal coefficient.

Example
Write the standard form.
7 × 10⁻²

7 × 10⁻²

The exponent is −2, so the decimal point makes 2 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

7
digit
.
 
stuff
× 10⁻²
2 swoops

The longer line is empty, so the coefficient is a whole number.

0.0721.
Fill with zeros.

0.07

Answer: 0.07

Example
Write the standard form.
6.2 × 10⁻⁴

6.2 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

6
digit
.
 
2
stuff
× 10⁻⁴
4 swoops
0.00064321.2
Fill with zeros.

0.00062

Answer: 0.00062

1
Write the standard form.
3 × 10⁻²
Show Answer

3 × 10⁻²

The exponent is −2, so the decimal point makes 2 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

3
digit
.
 
stuff
× 10⁻²
2 swoops

The longer line is empty, so the coefficient is a whole number.

0.0321.
Fill with zeros.

0.03

Answer: 0.03

2
Write the standard form.
7 × 10⁻⁴
Show Answer

7 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

7
digit
.
 
stuff
× 10⁻⁴
4 swoops

The longer line is empty, so the coefficient is a whole number.

0.00074321.
Fill with zeros.

0.0007

Answer: 0.0007

3
Write the standard form.
2 × 10⁻¹
Show Answer

2 × 10⁻¹

The exponent is −1, so the decimal point makes 1 swoop to the left.

Write digit . stuff × 10 to the number of swoops.

2
digit
.
 
stuff
× 10⁻¹
1 swoop

The longer line is empty, so the coefficient is a whole number.

0.21.

0.2

Answer: 0.2

4
Write the standard form.
9 × 10⁻³
Show Answer

9 × 10⁻³

The exponent is −3, so the decimal point makes 3 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

9
digit
.
 
stuff
× 10⁻³
3 swoops

The longer line is empty, so the coefficient is a whole number.

0.009321.
Fill with zeros.

0.009

Answer: 0.009

5
Write the standard form.
5 × 10⁻⁵
Show Answer

5 × 10⁻⁵

The exponent is −5, so the decimal point makes 5 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

5
digit
.
 
stuff
× 10⁻⁵
5 swoops

The longer line is empty, so the coefficient is a whole number.

0.0000554321.
Fill with zeros.

0.00005

Answer: 0.00005

6
Write the standard form.
8 × 10⁻²
Show Answer

8 × 10⁻²

The exponent is −2, so the decimal point makes 2 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

8
digit
.
 
stuff
× 10⁻²
2 swoops

The longer line is empty, so the coefficient is a whole number.

0.0821.
Fill with zeros.

0.08

Answer: 0.08

7
Write the standard form.
1 × 10⁻³
Show Answer

1 × 10⁻³

The exponent is −3, so the decimal point makes 3 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

1
digit
.
 
stuff
× 10⁻³
3 swoops

The longer line is empty, so the coefficient is a whole number.

0.001321.
Fill with zeros.

0.001

Answer: 0.001

8
Write the standard form.
6 × 10⁻⁶
Show Answer

6 × 10⁻⁶

The exponent is −6, so the decimal point makes 6 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

6
digit
.
 
stuff
× 10⁻⁶
6 swoops

The longer line is empty, so the coefficient is a whole number.

0.000006654321.
Fill with zeros.

0.000006

Answer: 0.000006

9
Write the standard form.
4 × 10⁻⁴
Show Answer

4 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

4
digit
.
 
stuff
× 10⁻⁴
4 swoops

The longer line is empty, so the coefficient is a whole number.

0.00044321.
Fill with zeros.

0.0004

Answer: 0.0004

10
Write the standard form.
3 × 10⁻⁵
Show Answer

3 × 10⁻⁵

The exponent is −5, so the decimal point makes 5 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

3
digit
.
 
stuff
× 10⁻⁵
5 swoops

The longer line is empty, so the coefficient is a whole number.

0.0000354321.
Fill with zeros.

0.00003

Answer: 0.00003

Decimal coefficients
11
Write the standard form.
2.5 × 10⁻²
Show Answer

2.5 × 10⁻²

The exponent is −2, so the decimal point makes 2 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

2
digit
.
 
5
stuff
× 10⁻²
2 swoops
0.0221.5
Fill with zeros.

0.025

Answer: 0.025

12
Write the standard form.
6.1 × 10⁻³
Show Answer

6.1 × 10⁻³

The exponent is −3, so the decimal point makes 3 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

6
digit
.
 
1
stuff
× 10⁻³
3 swoops
0.006321.1
Fill with zeros.

0.0061

Answer: 0.0061

13
Write the standard form.
8.4 × 10⁻¹
Show Answer

8.4 × 10⁻¹

The exponent is −1, so the decimal point makes 1 swoop to the left.

Write digit . stuff × 10 to the number of swoops.

8
digit
.
 
4
stuff
× 10⁻¹
1 swoop
0.81.4

0.84

Answer: 0.84

14
Write the standard form.
1.7 × 10⁻⁴
Show Answer

1.7 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

1
digit
.
 
7
stuff
× 10⁻⁴
4 swoops
0.00014321.7
Fill with zeros.

0.00017

Answer: 0.00017

15
Write the standard form.
9.2 × 10⁻⁵
Show Answer

9.2 × 10⁻⁵

The exponent is −5, so the decimal point makes 5 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

9
digit
.
 
2
stuff
× 10⁻⁵
5 swoops
0.0000954321.2
Fill with zeros.

0.000092

Answer: 0.000092

16
Write the standard form.
3.05 × 10⁻³
Show Answer

3.05 × 10⁻³

The exponent is −3, so the decimal point makes 3 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

3
digit
.
 
05
stuff
× 10⁻³
3 swoops
0.003321.05
Fill with zeros.

0.00305

Answer: 0.00305

17
Write the standard form.
4.8 × 10⁻²
Show Answer

4.8 × 10⁻²

The exponent is −2, so the decimal point makes 2 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

4
digit
.
 
8
stuff
× 10⁻²
2 swoops
0.0421.8
Fill with zeros.

0.048

Answer: 0.048

18
Write the standard form.
7.6 × 10⁻⁶
Show Answer

7.6 × 10⁻⁶

The exponent is −6, so the decimal point makes 6 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

7
digit
.
 
6
stuff
× 10⁻⁶
6 swoops
0.000007654321.6
Fill with zeros.

0.0000076

Answer: 0.0000076

19
Write the standard form.
5.3 × 10⁻⁴
Show Answer

5.3 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

5
digit
.
 
3
stuff
× 10⁻⁴
4 swoops
0.00054321.3
Fill with zeros.

0.00053

Answer: 0.00053

20
Write the standard form.
1.09 × 10⁻³
Show Answer

1.09 × 10⁻³

The exponent is −3, so the decimal point makes 3 swoops to the left.

Write digit . stuff × 10 to the number of swoops.

1
digit
.
 
09
stuff
× 10⁻³
3 swoops
0.001321.09
Fill with zeros.

0.00109

Answer: 0.00109

Easy 2

Scientific Notation

The decimal point is already written. Swoop right. The exponent is negative. Problems 1–10 have an integer coefficient. Problems 11–20 have a decimal coefficient.

Example
Write the number in scientific notation.
0.008

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 3 swoops.

0.008123.

Write digit . stuff × 10 to the number of swoops.

8
digit
.
 
stuff
× 10⁻³
3 swoops

The other digits are zeros, so the longer line stays empty.

8 × 10⁻³

Answer: 8 × 10⁻³

Example
Write the number in scientific notation.
0.0045

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 3 swoops.

0.004123.5

Write digit . stuff × 10 to the number of swoops.

4
digit
.
 
5
stuff
× 10⁻³
3 swoops

4.5 × 10⁻³

Answer: 4.5 × 10⁻³

1
Write the number in scientific notation.
0.05
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 2 swoops.

0.0512.

Write digit . stuff × 10 to the number of swoops.

5
digit
.
 
stuff
× 10⁻²
2 swoops

The other digits are zeros, so the longer line stays empty.

5 × 10⁻²

Answer: 5 × 10⁻²

2
Write the number in scientific notation.
0.0008
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 4 swoops.

0.00081234.

Write digit . stuff × 10 to the number of swoops.

8
digit
.
 
stuff
× 10⁻⁴
4 swoops

The other digits are zeros, so the longer line stays empty.

8 × 10⁻⁴

Answer: 8 × 10⁻⁴

3
Write the number in scientific notation.
0.3
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 1 swoop.

0.31.

Write digit . stuff × 10 to the number of swoops.

3
digit
.
 
stuff
× 10⁻¹
1 swoop

The other digits are zeros, so the longer line stays empty.

3 × 10⁻¹

Answer: 3 × 10⁻¹

4
Write the number in scientific notation.
0.00004
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 5 swoops.

0.0000412345.

Write digit . stuff × 10 to the number of swoops.

4
digit
.
 
stuff
× 10⁻⁵
5 swoops

The other digits are zeros, so the longer line stays empty.

4 × 10⁻⁵

Answer: 4 × 10⁻⁵

5
Write the number in scientific notation.
0.007
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 3 swoops.

0.007123.

Write digit . stuff × 10 to the number of swoops.

7
digit
.
 
stuff
× 10⁻³
3 swoops

The other digits are zeros, so the longer line stays empty.

7 × 10⁻³

Answer: 7 × 10⁻³

6
Write the number in scientific notation.
0.000009
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 6 swoops.

0.000009123456.

Write digit . stuff × 10 to the number of swoops.

9
digit
.
 
stuff
× 10⁻⁶
6 swoops

The other digits are zeros, so the longer line stays empty.

9 × 10⁻⁶

Answer: 9 × 10⁻⁶

7
Write the number in scientific notation.
0.02
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 2 swoops.

0.0212.

Write digit . stuff × 10 to the number of swoops.

2
digit
.
 
stuff
× 10⁻²
2 swoops

The other digits are zeros, so the longer line stays empty.

2 × 10⁻²

Answer: 2 × 10⁻²

8
Write the number in scientific notation.
0.0001
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 4 swoops.

0.00011234.

Write digit . stuff × 10 to the number of swoops.

1
digit
.
 
stuff
× 10⁻⁴
4 swoops

The other digits are zeros, so the longer line stays empty.

1 × 10⁻⁴

Answer: 1 × 10⁻⁴

9
Write the number in scientific notation.
0.6
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 1 swoop.

0.61.

Write digit . stuff × 10 to the number of swoops.

6
digit
.
 
stuff
× 10⁻¹
1 swoop

The other digits are zeros, so the longer line stays empty.

6 × 10⁻¹

Answer: 6 × 10⁻¹

10
Write the number in scientific notation.
0.000003
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 6 swoops.

0.000003123456.

Write digit . stuff × 10 to the number of swoops.

3
digit
.
 
stuff
× 10⁻⁶
6 swoops

The other digits are zeros, so the longer line stays empty.

3 × 10⁻⁶

Answer: 3 × 10⁻⁶

Decimal coefficients
11
Write the number in scientific notation.
0.047
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 2 swoops.

0.0412.7

Write digit . stuff × 10 to the number of swoops.

4
digit
.
 
7
stuff
× 10⁻²
2 swoops

4.7 × 10⁻²

Answer: 4.7 × 10⁻²

12
Write the number in scientific notation.
0.0038
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 3 swoops.

0.003123.8

Write digit . stuff × 10 to the number of swoops.

3
digit
.
 
8
stuff
× 10⁻³
3 swoops

3.8 × 10⁻³

Answer: 3.8 × 10⁻³

13
Write the number in scientific notation.
0.91
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 1 swoop.

0.91.1

Write digit . stuff × 10 to the number of swoops.

9
digit
.
 
1
stuff
× 10⁻¹
1 swoop

9.1 × 10⁻¹

Answer: 9.1 × 10⁻¹

14
Write the number in scientific notation.
0.00025
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 4 swoops.

0.00021234.5

Write digit . stuff × 10 to the number of swoops.

2
digit
.
 
5
stuff
× 10⁻⁴
4 swoops

2.5 × 10⁻⁴

Answer: 2.5 × 10⁻⁴

15
Write the number in scientific notation.
0.000062
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 5 swoops.

0.0000612345.2

Write digit . stuff × 10 to the number of swoops.

6
digit
.
 
2
stuff
× 10⁻⁵
5 swoops

6.2 × 10⁻⁵

Answer: 6.2 × 10⁻⁵

16
Write the number in scientific notation.
0.0104
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 2 swoops.

0.0112.04

Write digit . stuff × 10 to the number of swoops.

1
digit
.
 
04
stuff
× 10⁻²
2 swoops

1.04 × 10⁻²

Answer: 1.04 × 10⁻²

17
Write the number in scientific notation.
0.0057
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 3 swoops.

0.005123.7

Write digit . stuff × 10 to the number of swoops.

5
digit
.
 
7
stuff
× 10⁻³
3 swoops

5.7 × 10⁻³

Answer: 5.7 × 10⁻³

18
Write the number in scientific notation.
0.0000083
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 6 swoops.

0.000008123456.3

Write digit . stuff × 10 to the number of swoops.

8
digit
.
 
3
stuff
× 10⁻⁶
6 swoops

8.3 × 10⁻⁶

Answer: 8.3 × 10⁻⁶

19
Write the number in scientific notation.
0.46
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 1 swoop.

0.41.6

Write digit . stuff × 10 to the number of swoops.

4
digit
.
 
6
stuff
× 10⁻¹
1 swoop

4.6 × 10⁻¹

Answer: 4.6 × 10⁻¹

20
Write the number in scientific notation.
0.000709
Show Answer

The decimal point is already written in the number.

Swoop the decimal point right until one digit is in front of it. That is 4 swoops.

0.00071234.09

Write digit . stuff × 10 to the number of swoops.

7
digit
.
 
09
stuff
× 10⁻⁴
4 swoops

7.09 × 10⁻⁴

Answer: 7.09 × 10⁻⁴

Extra

Zeros in Small Numbers

Write the standard form, then count the zeros between the decimal point and the first nonzero digit.

Example
If 3 × 10⁻⁴ is written in standard notation, how many zeros are between the 3 and the decimal point?

Write the standard form first. The exponent is the number of swoops.

3 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

3 → 0.0003

The zeros between the decimal point and 3: 3.

Answer: 3

1
If 4 × 10⁻⁵ is written in standard notation, how many zeros are between the 4 and the decimal point?
Show Answer

Write the standard form first. The exponent is the number of swoops.

4 × 10⁻⁵

The exponent is −5, so the decimal point makes 5 swoops to the left.

4 → 0.00004

The zeros between the decimal point and 4: 4.

Answer: 4

2
If 9 × 10⁻² is written in standard notation, how many zeros are between the 9 and the decimal point?
Show Answer

Write the standard form first. The exponent is the number of swoops.

9 × 10⁻²

The exponent is −2, so the decimal point makes 2 swoops to the left.

9 → 0.09

The zeros between the decimal point and 9: 1.

Answer: 1

3
If 6 × 10⁻⁷ is written in standard notation, how many zeros are between the 6 and the decimal point?
Show Answer

Write the standard form first. The exponent is the number of swoops.

6 × 10⁻⁷

The exponent is −7, so the decimal point makes 7 swoops to the left.

6 → 0.0000006

The zeros between the decimal point and 6: 6.

Answer: 6

4
If 5.2 × 10⁻³ is written in standard notation, how many zeros are between the decimal point and the first nonzero digit?
Show Answer

Write the standard form first. The exponent is the number of swoops.

5.2 × 10⁻³

The exponent is −3, so the decimal point makes 3 swoops to the left.

5.2 → 0.0052

The zeros between the decimal point and 5: 2.

Answer: 2

5
If 1.08 × 10⁻⁴ is written in standard notation, how many zeros are between the decimal point and the first nonzero digit?
Show Answer

Write the standard form first. The exponent is the number of swoops.

1.08 × 10⁻⁴

The exponent is −4, so the decimal point makes 4 swoops to the left.

1.08 → 0.000108

The zeros between the decimal point and 1: 3.

Answer: 3

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