__Rules for determining significant figures__

**1. All
nonzero digits are significant.**

**2. All
zeroes between nonzero digits are significant.**

**3. Zeroes to
the right of a nonzero digit, but to the left of an understood**

** decimal point, are
not significant. **

** If
such zeroes are known to have been measured, however, they are **

** significant and
should be specified as such by inserting a decimal point to the**

** right of the last zero.**

**4. In numbers less than one, zeroes to the right of a decimal
point that are **

** to the left of the
first nonzero digit are never significant.
**

** They are simply placeholders.**

**5. In numbers less than one, the zero to the left of the
decimal point is **

** never significant.**

**6. All
zeroes to the right of a decimal point and to the right of a nonzero **

** digit are
significant.**

__Addition and Subtraction Involving
Significant Figures__

**In addition
or subtraction, the arithmetic result should be rounded off so that the final
digit is in the same place as the leftmost uncertain digit.**

__Multiplication & Division Involving
Significant Figures__

**The
arithmetic product or quotient should be rounded off to the same number of
significant figures as in the measurement with the fewest significant figures.**