Determine the number of significant figures in each of the following figures.

Question

1.) 2500

2.) 0.002300

3.) 146

4.) 0.00235

5.) 2500.0

6.) 3.92 x 10^-4

Answer 1

1.) 2500 2

2.) 0.002300 4

3.) 146 3

4.) 0.00235 3

5.) 2500.0 5

6.) 3.92 x 10^-4 3

Answer 2

The rules for counting the number of sig figs are these:

1) Numbers 1 - 9 always count as sig figs

2) Sometimes zeros count as sig figs, sometimes not:

1. Zeros between any number 1 - 9 count as sig figs such as the zeros in 3009 - this number has 4 sig figs.
2. Zeros to the left of an implied decimal point (where the decimal point is not shown), such as the zeros in 36000 do NOT count as sig figs - this number has 2 sig figs. These zeros are just placeholders.
3. Zeros to the left of shown decimal point DO count as sig figs such as the zeros in "3600." - this number has 4 sig figs. Exception: For a decimal number such as 0.456, the zero is not a sig fig (it is just a placeholder).
4. Zeros to the right of a decimal point that are between the decimal point and any numbers 1 - 9 do NOT count as sig figs such as the zeros in 0.00036 - this number has 2 sig figs. These zeros are just placeholders.
5. Zeros to the right of a decimal point that are trailing zeros (at the end of the number) DO count as sig figs such as the number 0.360 - this number has 3 sig figs.

Hopefully you will be able to determine the answers with these rules. Post your answers when you get done and I'll check them.