Help! I can't figure out Signifigant figures!?

Question

Calculate and enter in scientific notation. Enter your answer to three significant figures. (1.40x10-3)*(-1.84x105)2

Answer 1

After reading your question over, I think it is supposed to read (1.40x10^-3)*(-1.84x10^5)^2, am I correct? When denoting an exponent use the "^" before the number. Now.... let me see if I can help you.

(1.40x10^-3)*(-1.84x10^5)^2

square the second multiple first by squaring the number and then the exponents(when multplying exponents if the base is the same, add)
(-1.84 x 10^5)^2
(-1.84)^2 and (10^5)^2
(3.3856 x 10^7)

Your problem now reads
(1.40 x 10^-3)*(-3.3856 x 10^7)

now multiply the two numbers from each
1.40 x -3.3856 = -4.73984

then since the exponents have the same base, add the exponents
10^-3 x 10^7 =
-3 + 7 = 4
10^4

Now our preliminary answer is
-4.73984 x 10^4

To 3 sig digits, everything after -4.73 gets dropped because those numbers are not signifigant.
The correct answer would then be
-4.73 x 10^4

Answer 2

there are certain rules on sig figs.

1. all non 0 are significant. Ex: 12345.6789

2. when 0 is found on after a whole number, it is not significant. ex. 150 = 2 sig figs

3. when 0 is in the middle, it is significant. Ex; 504 = 3 sig figs

4. when 0 is after a decimal but there is a whole number before it, it is sifnificant. Ex; 5.40 = 3 sig figs

5. when 0 is before a decimal but without a whole number, then it isn't significant. Ex. 0.0004 = 1 sig fig

6. in addition or subtraction, count the dicimal place of the least.
ex. 1.0 + 1.000 + 2.53 = 4.530 ~ 4.5
(because 1.0 has the least decimal place)

7. in multiplication or division on the other hand, final answer should contain the same number of significant figure as the data with the least no of significant figure.
****note the difference of addition and multiplication. ****

Ex. 5.000 * 2.0 = 10.0000 ~ ~ 10 (because 2.0 has the least significant figure)



in multiplication, u count the significant figure. In addition on the other hand, u count the decimal places.


hope this helps.. ^_^

Answer 3

significant figures/digits is simply the number of digits from the left of the answer you leave when rounding. to 3 digits would leave and answer of xxx0000000000000 etc, with the decimal anywhere. there can be 0's to the left of the x if the x is to the right of the decimal.

Answer 4

Okay,
in sig figs, it is usually that the least precise number dictates what the number of decimals should be. In this case, the number 105 seems like it is the limiting number, so your answer should be rounded to the neares whole number (no decimals) because 105 has no decimals.

Answer 5

Here's pi to 1 significant figure:
3
Here's pi to 2 significant figures:
3.1
Here's pi to 3 significant figures:
3.14
Here's pi to 4 significant figures:
3.142
Here's pi to 5 significant figures:
3.1416
And to 15 significant figures:
3.14159265358979

Answer 6

(1.40*10-3)*(-1.84*105)2
=(14-3)*(-193.2)2
=11*-386.4
=-4250.4but 2,3,&10 have only one significant figure so the answer is only
-4000