how many significant figures are in these numbers 5.30cm and 0.000090lb?

Answer 1

5.30cm has 2 signifigant figures


0.000090lb has 5 signifigant figures.

Answer 2

The first one has three sig. figs. 5 and 3 are sig. figs, of course, but so is the 0 after the three. A 0 after the measured number AND after the decimal point is significant because it wouldn't be there unless it had been measured. (If the ruler used wasn't sensitive enough to record hundredths of a centimeter, the length would have been recorded as 5.3 cm rather than 5.30.)

The second one has two sig. figs. As before, the 9 is always significant, and the 0 after it is significant because if it weren't, it wouldn't be in that position. But the other 0s aren't. 0s before the measured number are never significant, no matter where they are in relation to the decimal point. It's easier to explain why in the metric system. If you had measured 0.000090 meters, you could rewrite it as 90 micrometers and have only two digits with no loss of accuracy, so that measurement can't have more than two sig. figs. The English system doesn't have the units to rewrite 0.000090 lb with only two digits, but the principle applies anyway.

Short answer: three in the first, two in the second.

Answer 3

5.30 cm has 3 significant figures. The trailing zero after the decimal place is significant.

0.000090 lb can be re-written in scientific notation as 9.0 E5 lb to make it easier to see that it has only 2 significant figures. All of those leading zeros between 9 and the decimal place are not significant, but the trailing zero is.


Rules for Determining Significant Digits:

* Non zero digits - non-zero numbers are significant

* Zeros - There are three types:
a) Leading zeros are zeros that precede all non-zero digits. These zeros are not significant figures.
b) Captive zeros are zeros between sig. figs., usually non-zero digits. These zeros are significant figures.
c) Trailing zeros are zeros at the right end of the number. They are sig. figs. only if the number contains a decimal point.

* Exact numbers are numbers that are derived by counting or by definition (for example: π or the rest mass of an electron). These numbers have infinite number of sig. figs.

Answer 4

5.30 has 3 significant figures...Any zeros to the right of digits after a decimal point are significant.

0.000090 has 2 significant figures. All of the zeros between the decimal point and the 9 are NOT significant.

Answer 5

2 and 2

Answer 6

5.30 there are 3

0.000090 there are 2 because all the zeros before the nine are null, any zero behind a number is significant

Answer 7

2
5