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Length is the distance between any two points. We use length to describe objects or to express the distance between two places almost every day. Length can be expressed in two systems of units: customary units and metric units. Here we will focus on the different metric units of length....Read MoreRead Less

Length is defined as the straight line distance between two points.

There are two points A and B and the distance between the two points is called ** length**.

With respect to the metric units, length is measured in units such as millimeters, centimeters, feet, yards, and miles.

Larger lengths such as the distance between two places or two countries are measured in miles. It is denoted by “mi”.

Smaller lengths are measured in inches, “in”, centimeters, “cm” or even in millimeters, “mm”.

Compared to the American Imperial measurement system, most of the world uses the “metric system” to measure quantities like length, time, weight(or mass). Even though there are different units for measuring such quantities, there are methods to convert these units from the Imperial system to the metric system.

For now we will focus on the measurement of length in the metric system, starting with the meter.

A meter length can be divided into 100 equal parts, each part measures 1 centimeter or “cm” as the abbreviated form.

That is, 1 m = 100 cm

or 100 cm = 1 m

Similarly, a centimeter can be divided into 10 equal parts, each part measuring 1 millimeter or “mm” as an abbreviation.

That is, 1 cm = 10 mm

or 10 mm = 1 cm

Now, if a meter is converted into millimeters, how many millimeters will constitute a meter?

1 m = 100 × 10 = 1000 mm

Also note that there is a larger unit of measurement that is the kilometer, which is equal to 1000 meters.

1 kilometer = 1000 meter.

We can also mention that, 1 m = 0.001 km.

These are the basic conversions regarding the units of length in the metric system – millimeters, centimeters, meters and kilometers.

**Example 1:**

Convert 0.61 m to centimeters.

**Solution:**

We know that,

1 m = 100 cm

⇒ 0.61 m = 0.61 × 100 cm

= 61 cm

**Example 2:**

A piece of fabric measures 2 m and 50 cm long. You need this measurement into meters.

**Solution:**

2 m + 50 cm

= 2 m + \(\frac{50}{100}\) m [Since, 100 cm = 1 m]

= 2 m + 0.5 m

= 2.5 m

**Example 3:**

Find the equivalent length and fill in the blanks in the following options.

i) 3 km = ______ m

ii) 2 m = ______ cm

iii) 7 cm = _____ mm

iv) 3 mm = _____ cm

**Solution:**

i) We know that, 1 km = 1000 m

⇒ 3 km = 3 × 1000 m

= 3000 m

ii) We know that, 1 m = 100 cm

⇒ 2 m = 2 × 100 cm

= 200 cm

iii) We know that, 1 cm = 10 mm

⇒ 7 cm = 7 × 10 mm

= 70 mm

iv) As we know that, 1 mm = 0.1 cm

⇒ 3 mm = 3 × 0.1 cm

= 0.3 cm

**Example 4:**

You have 40 mm of silver wire. You need \(3\frac{1}{2}\) cm of the same silver wire to make a ring. Do you have enough wire to make the ring? If not, what is the extra length of silver wire that is needed?

**Solution:**

Total length of wire you have is 40 mm.

Length of wire required to make the ring = \(3\frac{1}{2}\) cm = 3.5 cm

We know that 1 cm = 10 mm

⇒ 3.5 cm = 3.5 × 10mm

= 35 mm

On comparing the available length of wire and the wire required for the ring, We have 40 mm of silver wire as compared to the 35 mm required to make the ring.

Hence, no extra silver wire is needed and there is enough silver wire to make the ring.

Frequently Asked Questions

First, we recall the respective conversion factors. The basic rule to convert larger units into smaller units is to multiply, and to convert smaller units into larger ones, you have to divide.

For example, we know that 1 m = 100 cm

To convert 10 m into cm, we need to multiply by 100, so \(10\times 100=1000~ cm\)

To convert 10 cm into m, we need to divide by 100, so \(10\div 100=0.1~m\)

No, changing the units of measurement does not change the value of the length of the object. For instance, 1 m = 100 cm, that means the length of 1m is equivalent to 100 cm. They measure the same, they are just expressed differently.