how to do sig fig problem
[(286.8×105)−(1.300×103)]×2.8965

Question

how to do sig fig problem
[(286.8×105)−(1.300×103)]×2.8965

cuanchi · Answer

[(286.8×105)−(1.300×103)]×2.8965
     4sf     3sf      4sf      3sf       5sf


Multiplication and Division 
The LEAST number of significant figures in any number of the problem determines the number of significant figures in the answer. 

286.8×105 = 30114 = 3.01 x 10^4
    4sf    3sf                    3sf
you can mark the last significant figure and keep one extra for the calculations

1.300 ×103 = 133.9 = 134
  4sf      3sf                  3sf (rounded)
-----------------------------------
Addition and Subtraction
For addition and subtraction, look at the decimal portion
in your case both have none decimal figures
30114  - 134 =29980 
 no decimal places 

------------------------------
29980 × 2.8965 = 86837.07 = 86837
  5sf           5sf                           5sf

joannablackwelder · Answer

Are the 5 and 3 supposed to be exponents?

nnesha · Answer

yes.^

nnesha · Answer

$$[(286.8 \cdot 10^5) -1.300 \cdot 10^3)](2.8965)$$
 like this @katienic ?
type `^` to represent an exponent

cuanchi · Answer

If that is the case that change everything!!!!

for addition and subtraction with scientific notation the numbers has to have the  same exponential term in your case both have to have 10^5

(286.8 x 10^5) - (0.01300 x 10^5)

 286.8             x10^5
-   0.01300     x10^5
--------------
 268.78700     x10^5

keep the number of decimals as the lowest and rounded

268.8 x 10^5

basically it is the same number than the first in your calculation because the uncertainty of this number is bigger than the value that we want to subtract from it.