Units of Measurement
A unit of measurement is the definite magnitude of a quantity that is used as a standard for measuring the same kind of quantity. The meter, for example, is a unit of measurement that represents a specific length. When someone says “20 meters” (or 20 m), what they really mean is 20 times the predetermined length, referred to as a meter.
We multiply to convert from a larger to a smaller unit. To convert from a smaller to a larger unit, we divide.
When recording data, performing calculations, and reporting results, it is critical to include units. Units are universally recognized and essential for sharing information to maintain uniformity in measurement. For instance, if someone measures a room and says it is 25 finger spans long, it would be different when someone else measures it. When recording data or performing calculations, it is critical to include the units to ensure consistency.
Metric Units
The metric system uses the meter, liter, and gram as base units of length (distance), capacity (volume), and weight (mass), respectively. We use units derived from metric units to measure smaller and larger quantities. In the metric system, powers of ten can be used to find equivalent measures.
Kilo \((10^3)\) | Hecto \((10^2)\) | Deka (10) | Base unit (1) | Deci (0.1) | Centi (0.01) | Milli (0.001) |
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The table above depicts how metric units that are smaller or larger than the base unit are arranged. The units to the right of the base unit are smaller. Each unit becomes ten times smaller as we move to the right or one-tenth of the unit to its left. A ‘deci’ is one-tenth of the base unit, a ‘centi’ is one-hundredth of the base unit, and a ‘milli’ is one-tenth of a ‘deci’ or one-thousandth of the base unit. The units that lie on the left of the base unit are larger. Each unit to the left is 10 times larger than the unit to its right. A ‘deca’ is ten times the base unit, a ‘hecto’ is a hundred times the base unit, and a ‘kilo’ is a thousand times the base unit.
Customary Units
A set of weights and measures used to measure length, weight, capacity, and temperature is referred to as the customary system of measurement. It is also known as the United States Customary System because it is based on the English system of measurement. In the traditional system, length and distance are measured in inches, feet, yards, and miles. The standard weight measurement units in the United States are ounces, pounds, and tonnes. Ounces, cups, pints, quarts, and gallons are the most common capacity or volume measurement units in the United States.
The International System of Units, also known as the Modern Metric System, is the standard system that is universally used. Customary units are used mainly in the United States.
Length
Length is used to measure the distance between two points, such as the thickness or length of a credit card or the length of a tile. The meter is the source of all length units in the metric system.
1. 1 kilometer (km) = 1000 meters (m)
2. 1 hectometer (hm) = 100 m
3. 1 dekameter (dam) = 10 m
4. 1 meter (m) = 1 m
5. 1 decimeter (dm) = 0.1 m
6. 1 centimeter (cm) = 0.01 m
7. 1 millimeter (mm) = 0.001 m
In the United States Customary System, inches, feet, yards, and miles are used to measure length and distance. The conversions below can be used to convert one standard unit of length to another.
1. 1 foot (ft) = 12 inches (in)
2. 1 yard (yd) = 3 feet (ft)
3. 1 mile (mil) = 1760 yards (yd)
Solved Examples
Example 1. Convert 7 centimeters to millimeters.
Solution:
There are 10 millimeters in 1 centimeter.
Since you are converting from a larger unit to a smaller unit, you need to multiply.
7 x 10 = 70 millimeters.
So, 7 centimeters is equal to 70 millimeters.
Example 2. Convert 180 centimeters to meters.
Solution:
There are 100 centimeters in 1 meter.
Since you are converting from a smaller unit to a larger unit, you need to divide.
180 \(\div\) 100 = 1.8 meters.
So, 180 centimeters is equal to 1.8 meters.
Example 3. A giraffe has a tongue that measures about 0.4 meters in length. What is the length of its tongue in centimeters?
Solution:
There are 100 centimeters in 1 meter.
The mammal had a 0.4 meter long tongue. Convert a 0.4 meter into centimeters.
Since you are converting from a larger unit to a smaller unit, you multiply.
0.4 x 100 = 40 centimeters.
So, the length of the giraffe’s tongue is 40 centimeters.
Example 4. You walk 2.6 kilometers from your home to see a lake. After spending some time at the lake, you walk back home. You decide to take a break after 1,060 meters. So far, how many meters have you walked?
Solution:
Convert the distance of 2.6 kilometers to meters.
There are 1000 meters in 1 kilometer.
Since you are converting from a larger unit to a smaller unit, you need to multiply.
2.6 x 1000 = 2600 meters.
So, 2.6 kilometers is 2600 meters.
Now add the distance of 1,060 meters to 2600 meters. That will be 3660 meters.
So, the distance you walked = 3660 meters.
Example 5. Convert 92 inches to feet and inches.
Solution:
One foot has 12 inches.
Since you are converting from a smaller unit to a larger unit, you must divide.
\(92\div 12 = 7\frac{2}{3}\)ft. We know that 1 ft = 12 in, so \(\frac{2}{3}\) ft = \(\frac{2}{3}\) x 12 = 8 in
Therefore, 92 inches is 7 feet and 8 inches.
Example 6. Convert 4 miles to yards.
Solution:
There are 1760 yards in 1 mile.
Since you are converting from a larger unit to a smaller unit, you must multiply.
4 x 1760 = 7040 yards.
So, 4 miles in 7040 yards.
Example 7. A shark’s length is 8.6 feet. What would be its length in inches?
Solution:
Convert 8.6 feet to inches.
There are 12 inches in 1 foot.
Since you are converting from a larger unit to a smaller unit, you need to multiply.
8.6 x 12 = 103.2 inches.
So, the shark is 103.2 inches long.
Example 8. You need an 11.75 feet long cloth to make a dress. You have a cloth measuring 3\(\frac{1}{2}\) yards. Would this be enough? If not, how much more would you need?
Solution:
Convert 3\(\frac{1}{2}\) = 3.5 yards to feet.
There are 3 feet in 1 yard.
Since you are converting from a larger unit to a smaller unit, you need to multiply.
3.5 x 3 = 10.5 feet. You need cloth that is 11.75 feet long but you only have 10.5 feet, so you don’t have enough cloth. Let’s calculate how much more cloth you would need.
11.75 ft – 10.5 ft = 1.25 ft. So you would need 1.25 ft more to make that dress
The metric system is also known as a decimal-based system because it is based on the multiples of ten. By simply moving the decimal place, any measurement given in one metric unit (such as a kilogram) can be converted to another metric unit (such as a gram).
Except for the United States and a few other countries, the metric system was officially named the standard international unit (or SI). It is now used all over the world, except in the United States and a few other countries.