Honors Chemistry



Significant Figures Worksheet # 1

Indicate the number of significant digits in each number below and also state the rule number or numbers governing your decision.

Rule 1: In numbers that do not contain zeros, all the digits are significant.

3.1428 [5] 3.14 [3]

Rule 2: All zeros between significant digits are significant

7.053 [4] 7053 [4]

Rule 3: Zeros to the left of the first nonzero digit serve only to fix the position of the decimal point and are not significant.

0.0056 [2] 0.0789 [3] 0.000001 [1]

Rule 4: In a number with digits to the right of a decimal point, zeros to the right of the last nonzero digit are significant

43 [2] 43.0 [3] 43.00 [4] 0.00200 [3] 0.40050 [5]

Rule 5: In a number that has no decimal point, and that ends in zeros (such as 3600), the zeros at the

end may or may not be significant (it is ambiguous). To avoid ambiguity express the

number in scientific notation showing in the coefficient the number of significant digits.

|Number |# of significant digits |Rules governing your decision |

|1. 7474 | | |

|2. 707 | | |

|3. 70 | | |

|4. 450. | | |

|5. 0.001 | | |

|6. 0.0040 | | |

|7. 0.03030 | | |

|8. 5.320 | | |

|9. 1.305 x 104 | | |

|10. 5.6 x 10-3 | | |

Significant Figures Worksheet # 2

Indicate the number of significant digits in each number below and also state the rule number or numbers governing your decision.

Rule 1: In numbers that do not contain zeros, all the digits are significant.

3.1428 [5] 3.14 [3]

Rule 2: All zeros between significant digits are significant

7.053 [4] 7053 [4]

Rule 3: Zeros to the left of the first nonzero digit serve only to fix the position of the decimal point and are not significant.

0.0056 [2] 0.0789 [3] 0.000001 [1]

Rule 4: In a number with digits to the right of a decimal point, zeros to the right of the last nonzero digit are significant

43 [2] 43.0 [3] 43.00 [4] 0.00200 [3] 0.40050 [5]

Rule 5: In a number that has no decimal point, and that ends in zeros (such as 3600), the zeros at the

end may or may not be significant (it is ambiguous). To avoid ambiguity express the

number in scientific notation showing in the coefficient the number of significant digits.

|Number |# of significant digits |Rules governing your decision |

|1. 56000 | | |

|2. 700 | | |

|3. 567 | | |

|4. 950.05 | | |

|5. 0.20101 | | |

|6. 0.0650 | | |

|7. 0.070 | | |

|8. 5320. | | |

|9. 9.55 x 105 | | |

|10. 9.55 x 105 | | |

Significant Figures Worksheet # 3

How many significant figures are in each of the following numbers?

1) 5.40 ____ 6) 1.2 x 103 ____

2) 210 ____ 7) 0.00120 ____

3) 801.5 ____ 8) 0.0102 ____

4) 1,000 ____ 9) 9.010 x 10-6 ____

5) 101.0100 ____ 10) 2,370.0 ____

11) Why are significant figures important when taking data in the laboratory?

12) Why are significant figures NOT important when solving problems in your math class?

13) Using two different instruments, I measured the length of my foot to be 27 centimeters and 27.00 centimeters. Explain the difference between these two measurements.

14) I can lift a 20 kilogram weight over my head ten times before I get tired. Write this measurement to the correct number of significant figures.

Significant Figures Calculations Worksheet # 4

Solve each of the following problems and write their answers with the correct number of significant figures:

Calculating rules:

1. Multiplying or dividing – round results to the smaller # of sig. figs in the original problem.

2. Adding or subtracting - round to the last common decimal place on the right.

Rounding Rules XY -----------> Y

When Y > 5, increase X by 1

When Y < 5, don’t change X

When Y = 5, If X is odd, increase X by 1; If X is even, don’t change X

1) 4.5 + 2.34 = _________________________

2) 4.5 – 5 = _________________________

3) 6.00 + 3.411 = _________________________

4) 3.4 x 2.32 = _________________________

5) 7.77 / 2.3 = _________________________

6) 3.890 / 121 = _________________________

7) 1200 x 23.4 = _________________________

8) 120 x 0.0002 = _________________________

9) 78.5 + 0.0021 + 0.0099 = _________________________

10) (3.4 x 8.90) x (2.3 + 9.002) = _________________________

11) (2.31 x 103) / (3.1 x 102) = _________________________

12) 0.0023 + 65 = _________________________

13) (3.4 x 106) + 210,349 = _________________________

14) 1.09 x 3.498 + 2.45001 – 2.123 / 0.0023 = _________________________

15) Why is it important to always use the correct number of significant figures when solving a problem

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