**Rules for Determining ****Sig****nificant ****Fig****ures**
Significant figures are** critical **when reporting scientific **data** because they give the reader an idea of how accurately you could actually measure/report your data.
**The data is only as reliable as your least significant/accurate measurement
1) **ALL non-zero** numbers (1,2,3,4,5,6,7,8,9) are **ALWAYS** **significant**.
2) **ALL** zeroes** between** **non-zero** numbers are **ALWAYS****significant**.
3) **ALL** zeroes which are SIMULTANEOUSLY to the **right** of the decimal point **AND**
at the end of the number are **ALWAYS** **significant**.(see Atlantic & Pacific rule below)
4) **ALL **zeroes which are to the **left** of a written decimal point and are in a number >= 10
are **ALWAYS** **significant.**. (see Atlantic & Pacific rule below)
**A helpful way to check rules 3 and 4 is to write the number in scientific notation.
If you can/must get rid of the zeroes, then they are NOT **significant**.
**The Atlantic/Pacific Rule for Determining ****Sig****nificant ****Fig****ures **
1) look for the **P**resence, or **A**bsence, of a decimal point
- this will tell you which side to start counting from **P**acific:** left** **A**tlantic: **right**
__ __**P**acific __ __**A**tlantic
2) if there is a decimal point (**P**resence) you start counting from the **left side** of the number
- starting from the very** left side** of the number
- look for the first **non-zero** number
- count the **first non-zero** number and every number (0-9) after that
- __example:__ 0.00030
- because there is a decimal point (**P**resent), we start from the **left side** of the number
**left →**0.000**3**0, and look for the first non-zero number 0.000**3**0
- count that number and every number after that regardless of what the number is (0-9)
- in this case there are **2 sig****nificant ****fig****ures** - 0.000**30**
3) if there is not a decimal point (**A**bsence) you start counting from the **right side** of the number
- starting from the very **right side** of the number, look for the **first non-zero** number
- count the **first non-zero** number and every number (0-9) after that
- __example:__ 789000
- because there is no decimal point (**A**bsent), we start from the **right side** of the number
78**9**000 ← **right**, and look for the first **non-zero** number 78**9**000
- count that number and every number after that regardless of what the number is (0-9)
- in this case there are **3 sig****nificant ****fig****ures** - **789**000
**Share with your friends:** |