__What are significant figures?__- Also known as significant digits or simply "sig figs"

- They are certain digits in a measurement

- Associated with scientific notation and rounding

**What are they important?**- A measurement can never be precise. We use sig figs and scientific notation to find a general number.

__How do I know which are significant digits?__- Non-zero digits are sig figs

- Zeroes after the decimal point are sig figs

- Zeroes between 2 other significant digits are sig figs

- Leading Zeroes are NOT sig figs

- In scientific notation, all digits in front of the exponential term are sig figs

**Rounding**- Digit > 5, the digit in front of it rounds up

- Digit < 5, the digit in front of it keeps the same. All numbers after the rounded digit disappear.

- Digit = 5 + non-zero digits behind it, round up.

- Digit = 5 + no numbers behind it, round to make the digit even.

http://www.sciencegeek.net/APchemistry/APtaters/chap02counting.htm

This is a practice test on counting significant digits. Test yourself to see if you know the stuff!

- by Catherine

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