The Rules
1. Nonzero digits are always significant.
2. All final zeros after the decimal point are significant.
3. Zeros between two other significant digits are always significant.
4. Zeros used solely for spacing the decimal point are not significant.
When multiplying or dividing, your answer may only show as many significant digits as the least number of significant digits in the numbers multiplied or divided.
When adding or subtracting your answer
can only show as many decimal places as the measurement having the fewest number
of decimal places.