1. Significant Figures

2. Why should we be concerned which numbers are significant?
Significant Figures
In all numbers there are digits that are Significant
& others are not Significant.
Why should we be concerned which
numbers are significant?
1) Measurements are never exact.
2) Scientist want to record their data (nos.) with the
LEAST AMOUNT OF UNCERTAINTY.

3. It’s called the ATLANTIC - PACIFIC RULE
Significant Figures
To determine the number of significant figures in a number let’s take a look a technique that will help us figure it out
It’s called the ATLANTIC - PACIFIC RULE

4. Atlantic – Pacific Rule
1. Draw a map of the United States label the 2 oceans … which are???
PACIFIC
ATLANTIC

5. Atlantic – Pacific Rule
If a decimal point is Present in the number
start counting from the Pacific side (Left Side)
2. If a decimal point is Absent in the number
count from the Atlantic side (Right Side)
3. Begin counting all numbers from the first
NON-ZERO digit
- That number and all digits after it
(including zeros) are SIGNIFICANT

6. Atlantic – Pacific Rule
Let’s try some examples. How many significant
Figures are in the following numbers?
4 sig figs
3456
5 sig figs
6 sig figs
1 sig fig
20000
7 oranges
Infinite sig figs

7. Atlantic – Pacific Rule
Let’s try some more examples. How many sig figs
Are there in the following pairs of numbers?
750 vs. 750.
2 vs 3 sig figs
4 vs. 1 sig figs
1001 vs. 1000
3 vs. 4 sig figs
2.07 vs
vs 572
3 vs. 3 sig figs vs
4 vs 4 sig figs

8. Working with Significant Figures
It’s important we know how to manipulate Significant figures. We’ll need to know the same manipulations we needed to know for Scientific Notation, namely:
1. Addition
2. Subtraction -
3. Multiplication x
4. Division /

9. Working with Significant Figures
Let’s look at the rules that govern these mathematical operations.
1 & 2. Addition & Subtraction have the same rule
The number of decimal places in the Answer EQUALS the
Smallest Number of DECIMAL places in any of the nos.
Being added or subtracted.
Ex: =
= 18.7
= 3.013
= 3

10. Working with Significant Figures
3 & 4. Multiplication & Division have the same rule
The number of sig figs in the answer Equals the number of Sig Figs in the least precise number
Ex: x =
= 81.
/ = =