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How to Measure on a CM Ruler

Twelves inches in a foot, three feet in a yard, 1,760 yards in a mile -- the English system of length measurement is familiar but idiosyncratic. The metric system of length measurement, on the other hand, is rigorously formal and predictable. Metric units of length are based on multiples of 10. For example, there are 10 millimeters (mm) in 1 centimeter (cm), 10 centimeters in 1 decimeter (dm) and 10 decimeters in 1 meter (m).

Instructions

- 1
  Place a centimeter ruler on the table in front of you with the 0 marked on the ruler on your left.
- 2
  Read the highest number on the right end of the ruler. For example, if the highest number on the right side of your centimeter ruler is 15, you have a 15-centimeter ruler.
- 3
  Count the number of divisions between 0 and 1 on your centimeter ruler. Each one of these divisions represents one millimeter (mm). There are 10 millimeters in each centimeter of your ruler.
- 4
  Place an object you want to measure on the table. For example, you place a wooden block on the table in front of you.
- 5
  Place the centimeter ruler along one side of the object so that the first division line on the left side of the ruler is even with the left side of the object.
- 6
  Read where the right side of your object lies along the divisions of the ruler. It may be exactly even with one of the centimeter marks, or it may be between two of the centimeter marks. Note that if the right side of your object is perfectly even with a centimeter mark, your measurement is finished.
- 7
  Read the two centimeter marks the right side of your object lies between if the right side of the object does not lie perfectly even with one centimeter mark. For example, the right side of the top of your wooden block is between the 7 and the 8 centimeter marks on your ruler.
- 8
  Write the number of the lower centimeter mark on a piece of paper. This is how many centimeters are in your measurement. For example, write 7.
- 9
  Count the number of millimeter divisions between the centimeter mark you have written and the side of the object. For example, count seven millimeter divisions between the 7 on your centimeter ruler and the right side of the top of the wooden block.
- 10
  Write the number you have counted on a piece of paper. For example, write 7. This is the number of millimeters in your measurement.
- 11
  Add a decimal between the centimeter measurement and millimeter measurement, followed by the word "centimeters." For example, write "7.7 centimeters." Your wooden block is 7.7 centimeters wide.

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