
What Is a Ruler in Maths Definition Units Markings and How to Use It
Are you someone who looks at a ruler but doesn't understand how to use it? or do you ever wonder why so many different types of rulers are used? Why can’t just one ruler of 15 cm be sufficient? Vedantu will answer all these questions below. In this article, you will learn what is a ruler, its type, reading a ruler, and its uses.
Ruler Meaning in Maths - A ruler is a device or tool that is used in geometry and technical drawing, as well as engineering and construction technologies to measure the distance of a straight line. A math ruler is used to measure the length in both metric and customary units. The rulers are marked with standard distance in centimetres in the top and inches in the bottom and the intervals in the ruler are called hash marks.
Types of Ruler
There are different types of ruler depending on the material it is made of. Rulers are made from wooden, plastics and metal. Plastics are used to make rulers since they were invented as they could be moulded with length markings. Material rulers are used at a mechanical workshop. Sometimes a metal edge is embedded into a wooden desk ruler to preserve the edge when used for straight-line cutting.
Depending on the size of the ruler there are two types of ruler - a short ruler and a long ruler. Short rulers are 15 centimetres which are very convenient to carry and long rulers are 30 centimetres or 12 inches long, it is useful to draw larger drawings.
Line Gauge - This ruler is used in the paint industry and is made from a variety of materials, typically metal or clear plastics. The basic unit of measurement in the basic line gauge includes inches, agate, picas, and points.
Measuring Instruments - This instrument is made similar to the ruler function and they are portable by folding or retracting into a coil as in metal tape measure. When they are extended to use, It is straight as a ruler. For example, you can take a carpenter's ruler which is 2 m long and when it is folded, it's just 25 cm long, so that it can easily fit into the pocket.
Flexible Length Measuring Length - This instrument does not need to be straight, it is used by tailors to measure the fabric. The length of the tape is calibrated by inches and centimetres. It is used by a tailor to measure the solid body length, for example, a person's body. As well as linear length measurement, for example, a person's leg.
A Contraction Ruler - In this ruler there are larger divisions compared to the standard division, to allow the shrinkage of the metal casting. The contraction ruler is also known as the shrinkage or shrink ruler.
Screen Rulers - It is a type of ruler software programme, where you can have a digital scale on the screen by setting up the pixel. They are functional in both mobiles and the computer and it is useful in the absence of a physical ruler.
Measuring Objects Length using Ruler
To measure the length of any object, primarily place the first hash mark (which is at Zero marking) of the ruler, exactly at one end of the object. Then set the object along the ruler and then finally note down the final hash marks, which is the endpoint of the object. Refer to the above diagram for a better understanding of the process.
Reading Ruler
Ruler Measurements in Centimetre - A ruler will be having centimetre and millimetre markings. A centimetre is smaller compared to an inch. The hash marks with numbers on the upper side represent the centimetre. The millimetre is smaller than the centimetre, the smaller hash in between centimetres is known as a millimetre.
10 millimetres is equal to 1 centimetre.
1/10 = One-tenth of the cm.
3/10 = Three tenth of cm.
5/10 = Five tenth of cm.
8/10 = Eight tenth of cm.
1 is equal to 1cm.
Ruler Measurements in Inches - Inch is bigger than the centimetre. The big long hash with numbers opposite to the centimetre is known as the inches. There are a total of 16 sub hashes between the marking of one inch on the ruler.
Uses of a Ruler
After going through what is the ruler? We understood that ruler in maths is used to measure a line and the straight edges, which allows them to be used for drawing, scoring, and cutting. Many times they are also used in engineering, carpentry and the print fields.
Uses of Rulers in Geometry
In geometry, a ruler without having any marks on them could be used for drawing only a straight line between two points. It is also used to draw graphs and tables due to its straight edge.
It is used in the ruler and compass construction, where an unmarked ruler and compass can be used for construction. It is also useful in bisecting the angle by using an unmarked ruler and compass.
Do You know?
Which is the largest preserved ruler? Copper alloy rod is the oldest preserved ruler from c. 2650 BCE and it was by the German Assyriologist Eckhard Unger while excavating at Nippur.
Conclusion
A ruler is a tool that you will be encountering multiple times in your academic life. Each time it will come across in a different format and different least count, but the basic way of reading will remain the same.
After reading this article we have become aware of the importance of a ruler, its type and how it is read. Ruler is the most basic tool of geometry and also the most important one because only after learning to read it, you can proceed towards using other tools.
FAQs on Ruler in Mathematics Meaning and Practical Applications
1. What is a ruler in maths?
A ruler in maths is a measuring instrument used to measure and draw straight lines in units such as centimeters or inches. It is commonly marked with evenly spaced units that help measure length and distance accurately.
- Standard metric rulers measure in centimeters (cm) and millimeters (mm).
- Imperial rulers measure in inches and fractions of inches.
- It is also used to draw straight line segments in geometry.
2. How do you read a ruler in centimeters?
To read a ruler in centimeters, count the large numbered marks for centimeters and the smaller divisions for millimeters.
- Each big number represents 1 cm.
- Each small line between numbers represents 1 mm.
- Since 1 cm = 10 mm, ten small divisions make one centimeter.
3. How do you measure length with a ruler?
To measure length with a ruler, align one end of the object with the zero mark and read the value at the other end.
- Place the ruler straight along the object.
- Ensure the starting point matches the 0 mark.
- Read the measurement at the object's end.
4. What is the difference between a centimeter and a millimeter on a ruler?
The difference between a centimeter and a millimeter is that 1 centimeter equals 10 millimeters.
- A centimeter (cm) is a larger unit marked by numbered lines.
- A millimeter (mm) is a smaller division between centimeters.
- 10 mm together form 1 cm.
5. How many millimeters are in 1 centimeter on a ruler?
There are 10 millimeters (mm) in 1 centimeter (cm). This means each centimeter on a metric ruler is divided into ten equal small parts. For example:
- 2 cm = 20 mm
- 5 cm = 50 mm
6. How do you draw a straight line using a ruler?
To draw a straight line using a ruler, place the ruler firmly on the paper and draw along its edge.
- Mark the starting and ending points.
- Align the ruler edge with both points.
- Draw a line along the ruler's straight edge.
7. What is the formula for finding the length of a line segment using a ruler?
The formula for finding the length of a line segment using a ruler is Length = Final reading − Initial reading.
- Note the measurement at one end.
- Note the measurement at the other end.
- Subtract the smaller value from the larger value.
8. What are the common units marked on a ruler?
The common units marked on a ruler are centimeters and millimeters (metric) or inches (imperial).
- Metric rulers show cm and mm.
- Imperial rulers show inches divided into halves, quarters, or eighths.
9. What is the difference between a ruler and a measuring tape?
The main difference is that a ruler is rigid and short, while a measuring tape is flexible and longer.
- A ruler is usually 15 cm or 30 cm long.
- A measuring tape can measure several meters.
- Rulers are used for geometry and drawing; tapes are used for larger objects.
10. What are common mistakes when using a ruler?
Common mistakes when using a ruler include not starting at zero and misreading small divisions.
- Starting measurement from the edge instead of the 0 mark.
- Confusing mm with cm.
- Holding the ruler at an angle.





















