9/30/22 - Significant Figures

Question 1

Are non-zero numbers significant?

Answer 1

Yes, always

Question 2

Are zeros between non-zero numbers significant?

Answer 2

Yes, always

Question 3

When are trailing zeros significant?

Answer 3

When there is a decimal point at the end.

1.30 = 3 significant figures

2,400 = 2 significant figures
2,400. = 4 significant figures

Question 4

How many sig figs are in 0.00240?

Answer 4

3 sig figs

Question 5

How many sig figs are in 0.5078?

Answer 5

4 sig figs

Question 6

How many sig figs are in 8,090?

Answer 6

3 sig figs

Question 7

How many sig figs are in 0.800?

Answer 7

3 sig figs

Question 8

How many sig figs are in 92,000. ?

Answer 8

5 sig figs (note the decimal point)

Question 9

How many sig figs are in 3.460 x 10^-2

Answer 9

4 sig figs

Question 10

How do you determine significant figures in addition and subtraction?

Answer 10

The answer has the same number of decimal places as the measurement with the fewest decimal places.

Question 11

8.447 cm + 9.2 cm = 17.647. How should this be rounded for significant figures?

Answer 11

17.6 because 9.2 only has one decimal place.

Question 12

How do you determine significant figures in multiplication and division?

Answer 12

The answer has the same number of significant figures as the measurement with the fewest significant figures,

Question 13

9.2 cm x 6.8 cm x 0.3744 cm = 23.422464 cm^3. How should this be rounded for significant figures?

Answer 13

23 cm^3 because 9.2 and 6.8 have only 2 sig figs.

Question 14

What are exact numbers? What do they mean for significant figures?

Answer 14

Exact numbers have no uncertainty. Many are unit definitions or conversions, for instance. There are 60 minutes in an hour.

They do not limit the number of sig figs in a calculation.