1. WHAT IS A SIGNIFICANT FIGURE?
When you are making a measurement there are
always a certain number of known or certain digits.
Then as part of the measurement there will always
be a digit that is uncertain because it is your guess.
The known or certain digits plus the first unknown
Digit is referred to as the SIGNIFICANT FIGURES
Kenneth E. Schnobrich

2. PRECISION vs ACCURACY
PRECISION: this refers to a situation where the same
result is gotten each time you perform the operation
• repeatedly hitting the same spot in darts
ACCURACY: this refers to how close you come to
the accepted value or result
• how close you are to the bullseye

3. SIGNIFICANT FIGURES The following rules apply to significant figures:
All digits in a measurement are considered significant
Zeros that fall between digits are considered significant
Zeros to the right of a decimal and to the right of a non-zero are considered significant
If a decimal point is placed after a zero all of the intervening zeros are significant
Zeros after a digit but not followed by a decimal are not significant

4. EXACT NUMBERS These are usually numbers that are obtained by
counting rather than using a measuring device
such as a buret or graduated cylinder - 12 eggs in
dozen, 2 socks in a pair, 144 in a gross
© Kenneth E. Schnobrich

5. SIGNIFICANT FIGURES Working with Significant figures:
When you add or subtract numbers:
the final answer can have no more decimal places than the least precise value in the operation
2. When you multiply or divide numbers:
the final answer can have no more significant figures than the smallest number of significant figures in the operation

6. EXAMPLES ADDING & SUBTRACTING: 5.0043 4.032 1.02 3.2 5.0043 1.02 4.02
13.3

7. EXAMPLES
Multiplying and Dividing
4.91
5.0043
4.032
1.02
5.0043
20.33

8. MORE EXAMPLES How many Significant figures in each of the following:

9. MORE EXAMPLES How many Significant figures in each of the following:=
/4 =
x = = =

10. ROUNDING
When rounding use only the first digit to the right of the last significant figure becomes 4.3 if rounded to 2 sig.figs.
Rules:
In a series of calculations, carry the extra digits through to the final result, then round.
If the digit to be removed
Is less than 5 the preceding digit stays the same becomes 1.3
Is equal to or greater than 5, the preceding digit is increased by becomes 1.4