What is significant figures?
-Measure or meaningful digits.
-More preise mensthere are more significant digits.
A.Significant Digits
-The last digit in a measurement is uncertain as it could be one higher or one digit lower very eaily.
Eg. 2.78g on a balance : the 2&7 are CERTAIN number and 8 is UNCERTAIN
-The significant digits in the measurement includes all of the certain digits plus only the first uncertain digits.
Eg. the 2.78g has "3" significant digits
B.Significant Figures:Details
-Leading zero(s) aren't counted
Eg.0.01 has ONE siginificant digit
-Trailing zero(s) after the decimal point are counted
Eg.1.000 000 has SEVEN significant digits.
-Trailing zero(s) without a decimal point are NOT counted
Eg.1900 has Two significant digit.
C.Exact Numbers
-Some quantities are defined as exactly a certain amount and rounding is required.
Eg. A "pair" of shoes=2 shoes
D.Rounding Rules
-We round answers to the appropriate number of digits using rules similar to math with one set of exception.
-Look at the digits after the position of rounding.
1.Digit >5 , round up
Eg.64.36=64.4
2.Digit <5, round down
64.33=64.3
3.①Digit=5, more numbers (non-zero) after 5, round up
Eg. 64.35123=64.4
②Digit=5, ends at the 5, round to make the last digit EVEN(0.2.4.6.8)
Eg. 64.35=64.4
64.55=64.6
E.Math Rules 1. “+”&“--"
-When adding & subtracting, round to the fewest number of decial places
Eg 12.333
+ 20.1
-----------------
32.433
Round to 1 decimal place, the answer=32.4
Eg 12500
+ 6000
---------------
18500
Round to the thousands place (the first uncertain digit)=18000
F.Math Rules2 "× " & "÷"
-When multiplying or dividing, round to the fewest number significant
Eg. 12.01 4 sig figures
× 1.5 2 sig figures
------------------------
6.005
+ 12.01
---------------------------
18.015
Round to 2 sig figures (2<4) or the 1st uncertain digit.
Answer=18.02
Eg. Long Division
12.54÷1.3=9.64
Round to 2 sig figures
Answer=9.6
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