Non-zero digits are always significant. ex: 0.6789 has 4 significant figures
Any zeros between two significant digits are significant. ex: 502 has 3 significant figures.
One thing I will say is that I didn't know is that when there is a decimal, you count the zeros.ex: 705.001 has 6 significant figures
No decimals, means that they're ambiguous. They just happened to measure to the nearest thousand. You're not clear to count it.ex: 37,000
For addition and subtraction, look at the places to the decimal point. Add or subtract in the normal fashion, then round the answer to the LEAST number of places to the decimal point of any number in the problem.
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.This means you must know how to recognize significant figures in order to use this rule.