## Chem – Introduction to Significant Figures

What are significant figures?

Significant figures (Sig Figs) or, as some people call them, significant numbers, are a part of science that deals with numbers you get from measuring devices like a scale or a ruler. It is a system to tell you how far you can trust your measurement numbers or to put it another way, how accurate they are. What you do for significant figures is count each place (decimal place) in any figure or number you are given.

For example:

96000

How many number places are in 96000?   5

How significant figures are in 96000?   2

What I am trying to highlight is that there is a difference between how many number places (decimal places) that are shown in a written number and how many we actually count in science (significant figures). Throughout the rest of this section I will teach you how to count the significant figures correctly, but first let us talk about the terminology around significant figures.

What is the terminology surrounding significant figures?

When we describe how to break down significant figures we divide numbers (0 to 9) into two categories. The first category is the ZERO. Zeros can mean different things in science so we have to make a special category for them. The second category is the NON-ZERO numbers (1,2,3,4,5,6,7,8,9). All the non-zero numbers are treated the same way when we use significant figures so they all go in the same category.

We can further break down ZEROS into where they are relative to the NON-ZERO numbers. ZEROs can be three different places.

ZEROs can be to the LEFT of NON-ZERO numbers.   Example: 0.0047

ZEROs can be BETWEEN NON-ZERO numbers.   Example: 2008

ZEROs can be to the RIGHT of NON-ZERO numbers.   Example: 6300

Examples: Determine if the number has ZEROs BETWEEN, to the RIGHT of, or to the LEFT of NON-ZERO numbers. More than one answer is possible. VIDEO demonstration of determining where the ZEROs are from the examples below.

 Number Where are ZEROs? 0.00145 Left 2500 Right 84005 Between 0.07009 Left and Between 03108600 Left and Between and Right

PRACTICE PROBLEMS: Determine if the number has ZEROs BETWEEN, to the RIGHT of, or to the LEFT of NON-ZERO numbers. More than one answer is possible.

 Number Where are ZEROs? 420 Right 0.837 Left 0.05206 Left and Between 3014 Between 0.6705090 Left and Between and Right  