1. Significant Figures

2. The Basics  All nonzero digits are significant  Ex: 1.2 – 2 significant digits  Ex: 1.2341 has 5 significant digits  Zeroes between nonzero digits are significant  Ex: 1008 has 4 significant digits  Ex: 5.007 has 4 significant digits

3. The Basics  Leading zeros to the left of the first nonzero digits are not significant; such zeroes merely indicate the position of the decimal point  Ex: 0.0001 has 1 significant digit  Ex: 0.0012 has 2 significant digit  Trailing zeroes that are also to the right of a decimal point in a number are significant  Ex: 0.020 has 2 significant digit

4. The Basics  When a number ends in zeroes that are not to the right of a decimal point, the zeroes are not necessarily significant  Ex: 290 may have 2 or 3 significant digits.  Exception to this rule is the use of scientific notation. All digits in the first part of a scientific notated number are significant.  Ex: 5.0020 x 10 6 has 5 significant digits

5. Exact Numbers  Some numbers are known to be exact. These are often used as conversion factors as discussed yesterday.  There are exactly 12 inches in 1 foot.  There is exactly 100 cm in 1 meter.

6. Math Rules  When performing a math problem, the number in the problem with the least amount of significant digits determines the answer.  Ex: 5.86 x 21.5482 = 126.272452. This should be rounded to 3 significant digits, 126.