How many significant figures are in these 3 numbers?

Question

1) 0.000720

2) 5000.0

3) 68400.20

thanks, i'm really confused :]

Answer 1

1) 0.000720 has 5 significant figures (the first zero and the ending zero have no significance).

2) 5000.0 has 4 significant figures (the ending point zero has no significance).

3) 68400.20 has 6 significant figures (the ending zero has no significance).

Answer 2

1) 3

2) 5

3) 7

Answer 3

3

5

7

Answer 4

1) There are 3 SF (720). The zeros in front are NOT significant, just place holders. The last zero IS significant because it's to the right of the decimal place and follows non-zero numbers.

2) There are 5 SF (all digits). Since there is a zero to the right of the decimal place you must assume that it's not just a place holder. Otherwise, it need not be there. If it is significant, all the other zeros before it are, too.

3) There are 7 SF (all digits). The zeros between 4 and 2 (two nonzero numbers) are significant. The last zero is also significant for the same reason it is in problem 1.

Answer 5

1) 0.000720

3

you won't count the zero's before the numbers.

2) 5000.0

5

it has five because there is a decimal point after the 3rd zero, if it was just 5000 then it would only be one significant figure

3) 68400.20

7

all of the numbers are sig figs,  

Answer 6

1. 3

you don't count the zero's before the numbers (unless it is in b/w two non zero integers)

2. 4

it has four because there is a decimal point after the 3rd zero, if it was just 5000 then it would only be one significant figure

3. 7

all of the numbers are sig figs, the two zero's are in b/w 4 and 2 and there is a zero after the 2