Long and Short Class 4 NCERT: Chapter 2 Guide

In CBSE Class 4 Maths Chapter 2 Long and Short, you learn how to understand length in everyday life. Length tells us how long, short, tall, wide or far something is. We compare pencils, ribbons, roads, heights of people, distances between places and many other things using length. In this chapter, you will practise choosing the correct unit, measuring with a ruler or measuring tape, estimating before measuring, and converting between metres and centimetres. You will also see why using body parts like handspans can give different answers for different people, while standard units like centimetre and metre give the same answer for everyone. By the end, you will be able to compare lengths, arrange them from shortest to longest, solve simple word problems, and explain your steps clearly like in NCERT solutions class 4 maths long and short.

What Long and Short Means

Length is the measure of how far something goes from one end to the other. A pencil has length, a table has length, and the distance from your classroom to the playground also has length. In Class 4, you do not only say bigger or smaller; you learn to use proper measuring words. A short object may be measured in centimetres, such as an eraser that is 5 cm long. A longer object, such as a door, is better measured in metres. A very long distance, like the distance between two cities, is measured in kilometres. Good measuring begins with choosing a suitable unit.

Important Measurement Words

Length: The distance from one end of an object to the other end.
Centimetre or cm: A small unit used to measure short objects like a pencil, spoon, leaf or notebook edge.
Metre or m: A bigger unit used to measure longer things like a room, rope, blackboard or height of a person.
Kilometre or km: A unit used for very long distances, such as the distance from home to school if it is far away.
Estimate: A sensible guess made before measuring exactly. Estimating helps you check whether your final answer is reasonable.

How to Choose the Right Unit

YoLearn Sketchpad Method for Measuring with a Ruler

Place the zero correctly — Keep the starting end of the object exactly at 0 on the ruler, not at 1. If you start at 1 by mistake, your answer becomes 1 cm less or more than the true length.
Look straight down — Read the mark by looking from above, not from the side. Looking from the side can make the mark seem different, especially for small objects.
Read the ending mark — Find where the other end of the object reaches. If a pencil begins at 0 and ends at 14, its length is 14 cm.
Write the unit — Always write cm, m or km with the number. The answer 14 is incomplete, but 14 cm tells the exact length unit.

Worked Examples

Example 1: Compare 145 cm and 1 m 60 cm. Step 1: Convert 1 m 60 cm into centimetres. Since 1 m = 100 cm, 1 m 60 cm = 100 cm + 60 cm = 160 cm. Step 2: Compare 145 cm and 160 cm. Step 3: 160 cm is greater than 145 cm. Final answer: 1 m 60 cm is longer than 145 cm.
Example 2: A rope is 3 m long. Riya cuts 75 cm from it. How much rope is left? Step 1: Convert 3 m into centimetres: 3 m = 300 cm. Step 2: Subtract the cut part: 300 cm - 75 cm = 225 cm. Step 3: Convert 225 cm into metres and centimetres: 225 cm = 2 m 25 cm. Final answer: 2 m 25 cm of rope is left.
Example 3: Arrange 2 m, 175 cm and 1 m 90 cm from shortest to longest. Step 1: Convert all lengths to centimetres. 2 m = 200 cm. 1 m 90 cm = 190 cm. Step 2: Now compare 200 cm, 175 cm and 190 cm. Step 3: The order is 175 cm, 190 cm, 200 cm. Final answer: 175 cm, 1 m 90 cm, 2 m.

Common Mistakes to Avoid

Do not start measuring from 1 on the ruler. Start from 0 unless your teacher specifically shows another method.
Do not forget units. Writing 8 instead of 8 cm can make the answer unclear or wrong.
Do not compare different units without converting. First change metres to centimetres or centimetres to metres and centimetres.
Do not use kilometres for small objects. A pencil cannot be 12 km long; it may be 12 cm long.
When subtracting lengths, convert mixed units like 2 m 30 cm into centimetres if subtraction looks confusing.

NCERT Exam Tip

In word problems from cbse class 4 long and short, underline the unit words before solving. If the question has both m and cm, convert everything into cm, do the calculation, and then write the answer back in m and cm if needed. This keeps your working neat and avoids place-value mistakes.

Practice Questions with Solutions

Q: Which is longer: 125 cm or 1 m 30 cm? A: Step 1: Convert 1 m 30 cm into centimetres: 100 cm + 30 cm = 130 cm. Step 2: Compare 125 cm and 130 cm. Step 3: 130 cm is greater than 125 cm. Final answer: 1 m 30 cm is longer.
Q: A ribbon is 2 m 40 cm long. How many centimetres long is it? A: Step 1: Remember that 1 m = 100 cm. Step 2: Convert 2 m into centimetres: 2 m = 200 cm. Step 3: Add the extra 40 cm: 200 cm + 40 cm = 240 cm. Final answer: The ribbon is 240 cm long.
Q: Meena walks 85 m from her house to a shop and then 60 m from the shop to a park. How far does she walk in all? A: Step 1: Add the two distances because we need the total distance. Step 2: 85 m + 60 m = 145 m. Step 3: Check the unit; both are in metres, so no conversion is needed. Final answer: Meena walks 145 m in all.
Q: Arrange these lengths from shortest to longest: 90 cm, 1 m 10 cm, 75 cm, 1 m. A: Step 1: Convert metre lengths into centimetres. 1 m 10 cm = 110 cm and 1 m = 100 cm. Step 2: Compare all lengths: 90 cm, 110 cm, 75 cm, 100 cm. Step 3: Order from smallest to greatest: 75 cm, 90 cm, 100 cm, 110 cm. Final answer: 75 cm, 90 cm, 1 m, 1 m 10 cm.

Frequently Asked Questions

What is the main idea of Long and Short Class 4 NCERT?

The chapter teaches how to compare, measure and estimate lengths. Students learn to use standard units like centimetre, metre and kilometre instead of only saying long or short.

Why do we use standard units for measurement?

Body measures like handspan and footstep can be different for different people. Standard units give the same measurement for everyone, so answers become fair and clear.

How do I convert metres into centimetres?

Use the rule 1 metre = 100 centimetres. Multiply the number of metres by 100, and then add any extra centimetres if given.

What is the best way to solve mixed m and cm problems?

First convert the whole length into centimetres, then add or subtract. At the end, you can convert back into metres and centimetres to make the answer easier to read.