GEAR UP FOR LIFE

MATH MENTOR: Measuring distances and spaces
 

The Metric Ruler

A metric ruler is easy to read. There are 10 millimeters to each centimeter. Count them if you want. Between the 0 and the 1, there are ten millimeters.

English rulers are more difficult to read because they use fractions. One inch on a ruler can be divided into 8 parts or fractions. (They could also be divided into 16 parts or fractions.) In the green ruler below, each inch is divided into 8 parts. One part (space) would be called 1/8 of a fraction.

Look at the chart below. Now that you know each system, you can convert from one to another. Inches are smaller than centimeters. It doesn't matter what system you use, as long as everyone agrees on the distances.

English System Metric System Formula
1 in 2.54 cm inches to centimeters: in X 2.54

Example: How tall is a 5.5  (65 inches) woman  in centimeters?   65X2.54=5.1 cm
1 ft 3.05 dm
feet to decimeters: ft X 3.05

Example: You want to order 50 strips of metal that are 2 feet long. The company only deals with metric measurements. What length would you ask for?
2 ft X 3.05 dm= 9.15 dm or 91.5 cm (9.10 X 10)

A dm is 1/10 of a meter. If you could divide 3.05 by 10 (just move the decimal point) and state that 1 ft is approximately .3 m, or exactly .305 m.
1 yd 0.91 m yards to meters: yd X .91

Example: You want to order 12 yards of material from Brazil. How much would you order in meters?
12 yd X .91 m = 10.92 meters
1 mi 1.61 km miles to kilometers: mi X 1.61

Example: Your American map says that the distance between two European cities is 45 miles. You will need to calculate that in kilometers. How far would it be on a European map?
45 mi X 1.61 km = 72.45 km

 

You Try It!

Fill in the missing expressions.

EXAMPLE:  
2 in 5.08 cm

 

3 ft dm m
1.5 mi km yd
4.5 m km m
3.5 ft cm dm

To practice, go to http://www.teaching-english-in-japan.net/conversion/