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# Sig. figures question?

When you do multiplication or division, the rule is that your answer will have the number of significant figures of the smallest number in the original question right?

What is the rule for addition and subtraction, then what significant figure rules is your answer supposed to follow?

### 1 Answer

- 1 decade agoFavorite Answer
Significant figures can be a tricky concept if you don't thoroughly understand the rules. While these rules are basic, it's in your best interest to master them properly as it's very easy to confuse them.

The rule for addition and subtraction of SF's is that your answer can only have as many significant digits or figures as the number with the least amount of decimal places.

Ex: 0.5 + 2.983 - 1.69887 = calculator answer [1.78413] ===> However, this answer is false in terms of SF's because your final answer can only contain as many digits as the number with the least amount of decimal places. 0.5 is the number with the least amount of decimal places; it only has 1 decimal place which is the tenths place. So your final answer ends up being 1.8 rounded to the tenths place.

Also, you have the right idea for multiplication and division. I honestly think the SF's rule for adding and subtracting is the hardest to remember because in my classes, it's the rule we use the least so I often have to think about this rule as opposed to the other rule.

Good luck and I hope this helped!

Source(s): School