Significant+Figures+&+Zeros

Defination of significant Figures: a measured or meaningful digit.(Text P.27) Why we need to use Significant Figures? --The Significant Figures of a number are digits that has meaning to make the measurement more precise and accuracy.

The rules for identifying sigificant digits: EX: -- 27 has two significant figures : 2 and 7 -- 3.27 ahs three significant figures: 3, 2 and 7 EX: --102.1 has four significant figures : 1,0,2,and 1 --120.02 has five significant figures: 1,2,0,0,and 2 EX: --0.102 has three significant figurres: 1,0,and 2 --0.0025 has two significant figures: 2 and 5 EX:-- 32700 has three significant figures: 3,2,and7 -- 0.023400 has five significant figures:2,3,4,0,and 0 THE SIGNCANT FIGURES OF A NUMBER ARE COUNT FROM LEFT TO RINGT STARTED WITH THE FIRST NON-ZERO DIGIT. EXCEPTION:when you do the caculation, you should following the "least rule".
 * All non-zero digits are considered to be useful significant.
 * If there are zeros appearing between two non-zero digits, the Zeros are considered as significant
 * If the zeros are leading the beginnning of the number, the zeros are not significant.
 * Trailing zeros in a number that contain a decimal point considered as significant.

If you add and subtract two numbers, the result should have the least decimal place EX:- 12.3+3.45=15.7 not 15.75 explanation:12.3 has one decimal place ,3.45 has two decimal place, the least decimal place is 1,so the result is rounding off to1 decimal place. EX:- 0.111+0.9=1.0 not 1.011 explanation:0.111 has three decimal places, and 0.9 has one decimal place,so the least decimal place is 1,so the result is rounding off to 1 decimal place.

If there is no decimal place in one of the numbers,choose the least sig figs. EX: 230+48.44=280 not 278.44 explanation:the least sig fig of two numbers is 2,so the result should has two sig figs.

If two number are times or divided, choose the least sig figs. EX: 15.01*731.205=109800 not 109756.197 explanation:the least sig figs of two numbers is four ,so the result has 4 sig figs.

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