You look at the markings on its edge.
A ruler has markings, a straight edge does not. In "straight edge and compass" constructions, you are not allowed to mark the straight edge. Things that are impossible using only a straight edge and compass are possible if markings are allowed (for example, it's possible to trisect an angle using a marked straight edge).
12 inches = 30.48 centimetres. However, the centimetre markings usually stop at 30 cm.
A decimeter is a unit of length in the metric system, equivalent to one-tenth of a meter. On a standard ruler with centimeter and millimeter markings, the decimeter would typically be represented by the centimeter markings. Therefore, each decimeter would be equal to 10 centimeters on the ruler.
They are in fact two different devices that are commonly mistaken. A "measuring stick" is a stick of a given length that is used to reference another object from it's total length. These usually have no markings as such, or any calibrated length. A "ruler" (aka straightedge) IS calibrated and has measurement markings. It is used to "rule" straight lines to an exacting measurement. Originally designed for the engineering industry, they have been useful in countless other areas throught history. A 2 second google search revealed this: http://en.wikipedia.org/wiki/Ruler
a straightedge
The answer depends on the graduation (markings) on the ruler.
Called a straight edge
a bit of plastic
You look at the markings on its edge.
It is between 1.3 and 1.4: nearer to 1.4. It is 1 3/8 if your ruler has markings in eighths.
On a 30cm ruler you can't get it exactly, you need a higher tech ruler which has the markings of 2.54cm. If you have a normal ruler you have to estimate.
A precision unit of a ruler typically refers to the smallest increment of measurement marked on the ruler. For example, a ruler with millimeter markings has a precision unit of 1 millimeter.
That depend on how long the ruler is. The 2 rulers in my desk drawer have 200 and 300 milimeters markings respectively. I also have a triangle with 195 millimeter markings on one side. I just looked in another drawer and found a ruler with 400 mm markinga and a folding carpenter's rule with 2000 markings.
To measure in millimeters (mm), use a ruler or measuring tape with markings in millimeters. To measure in centimeters (cm), use a ruler or measuring tape with centimeter markings. For meters (m), use a meter stick or measuring tape with markings in meters. Simply align the start point of the object you are measuring with the zero mark on the ruler or tape and read the measurement at the endpoint.
The distance between the 0 and 1 markings on a metric ruler.
On a standard ruler, 1.5cm would be the distance between the 1cm mark and the 2cm mark. It's a relatively small distance and can be found by eyeballing or using the measurement markings on the ruler.