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Homework: Significant Figures 1

There are six rules on determining how many significant figures are in a number:

1. Non-zero digits are always significant
2. Any zeros between two significant digits are significant; for example, 603
3. Trailing zeros in the decimal portion only are significant; for example, 6.0 but not 60
4. Placeholder zeros are not significant; for example, the zeros in 36,000 or 0.00064
5. Zeros which are normally placeholders can be considered significant if a decmal point appears at the end of the number; for example, 400 has 1 s.f. but 400. has 3
6. Exact numbers have an ‘infinite’ number of significant figures; for example π using the π button on your caclulator, 100 yr = 1 century, defined quantities like c = 2.99792458 × 108 m/s, ratios, constants like 4/3 in V = 4/3πr3

Why does it matter? Significant figures tell you how precise your number is. The more significant figures, the more precise the number.

Determine the number of significant figures:
1. 7.890 ________
2. 0.003 ________
3. 600,000 ________
4. 3.0800 ________
5. 0.00418 ________
6. 91,600 ________
7. 0.003005 ________
8. 250 ________
9. 780,000,000 ________
10. 0.0101 ________
Underline the significant zeros:

1. 0.00800
2. 0.00500
3. 1.000
4. 1,000,002
5. 6,002,300,000
6. 0.00893
7. 2.070
8. 20
9. 6,008
10. 705,000
Circle the number with greater precision:
1. 40 m    40. m
2. 540 cm    5.40 m
3. 2704 g    2740 g
4. 823.0 L    8230 L
5. 456.0 g    456,000 mg
6. 420 cm    402 cm
7. 99.75 L    9,973 mL
8. 412,001 μm     7,000,000 nm
9. 512 mg    0.5120 g
10. 19 L    1,900. mL

1. An archaeologist finds that the fossil human ancestor she discovered is about 2,000,000 years old. How old will the fossil be in one year?
Last updated: Oct 01, 2006 Home