Question

wht Are In Significant Figures

Answer 1

for understanding significant figures ,we  see one example what is it in actual and what is the importance in science ?
 
       Let I said that i bought  a home with $20,000 . but my friend who was buying the same home said the price of home was $20,000.12. the information from both source are correct. but it was given to different degree of accuracy.
$20,000.12 might have been the exact number. when we round off $20,000.12 to one significant figure then it will be $20,000

according to above example you can observe that,
the accuracy of any answer depends upon number of significant figures. the answer will be more accurate when it is given to a higher number of significant figures.

           it means significant figures give us idea about which answer is  more accurate .

Let see one more example :- a body moves in straight path 200m in 30 sec, then find the speed of that body ?
      you got,
          speed = distance/time = 200/30 = 20/3 m/s = 6.666666 m/s
and other student -A said that, the answer is 6.67 m/s
  student -B said that, the answer is 6.7 m/s

you see all are different. but i said that the accuracy of answer is depend upon the number of significant figures.
so, first of all you have to find out number of significant figures of all answers.

for your answer-- number of significant figures = 7
 student -A - number of significant figures = 3
student - B - number of significant figures = 2
 hence, you can say your answer is more accurate than other user answers.
[note :- here, i am not applying rule of significant figures , just give you example how it is in actually?]
 
     
 

Answer 2

Answer:

The digits of a number representing a measurement that are definitely known known, plus one more digit at the end which is estimated are called significant digits (or) figures.

Example:- Suppose least count of a scale used to measure length of a rod is 0.1 cm. Suppose one end of the rod is coinciding with zero of the scale and the other end is in between two marks reading 14.5 cm and 14.6 cm.

So length of the rod is more than 14.5 cm but less than 14.6 cm.

One observer may think that the correct measurement is perhaps 14.52 cm

Here 1 , 4 and 5 are reliable and last digit 2 is a guess and thus not reliable.

So in 14.52 cm there are ''4'' significant figures.

   The last significant figure is called the 'first doubtful figure' or the 'least significant figure'. It is also called ''uncertain digit'. It is 2 in 14.52 cm.