Exercise 1 Page P3

We will review what we know about metric units of length. Let's start by taking a look at the table below which shows different units.

Metric Units of Length
$1$ kilometer = $1000$ meters
$1$ meter = $100$ centimeters
$1$ centimeter = $10$ millimeters

Note that when we need to convert from smaller to larger units, we multiply. When we want to convert from larger to smaller units, we divide. Now let's assume that we measured our keyboard and found that it is $40$ centimeters long.

We will convert this measure to both larger and smaller metric units. Let's begin with the smaller unit, millimeters. Notice that there are $10$ millimeters in each centimeter. We found that our keyboard is $400$ millimeters long. Now let's convert $40$ centimeters to kilometers, which are considerably larger than centimeters. To do so, we need to first change centimeters to meters. Since $1$ meter is $100$ centimeters, we need to divide by $100.$ Next, because there are $1000$ meters in $1$ kilometer, we can change meters to kilometers by dividing the result by $1000.$ Finally, we found that our keyboard is $400$ millimeters, or $0.0004$ kilometers, long.