Significant Figures

Significant figures are:

"the minimum number of digits needed to write a given value in scientific notation without loss of accuracy"

The most significant figure is the left-hand most digit, the digit which is known most exactly.
The least significant figure is the right-hand most digit, the digit which is known least exactly.

Significant figures are important when reporting scientific data because they give the reader an idea of how accurately data has been measured. Here are the rules:

All non-zero numbers (1,2,3,4,5,6,7,8,9) are significant.
All zeroes between non-zero numbers are significant.
All zeroes which are both to the right of a decimal point AND at the end of a number are significant.

Examples:

Number:	# Significant Figures:	Rule(s):
12,345	5	1
1.234	4	1
100.02	5	1,2
0.0001	1	1
1.2000	5	1,3
102.030	6	1,2,3
1,000,000	1	1
10.0	3	1,3

Unless you are told otherwise, use the same number of significant figures in your answer as are given in the question.