Decimals on a Number Line
A number line is a straight line on which every point represents a number. Decimals can be shown on a number line by dividing the space between two whole numbers into 10 equal parts (for tenths) or 100 equal parts (for hundredths).
Plotting decimals on a number line helps you visualise their value, compare them, and understand the order of decimal numbers.
What is Decimals on a Number Line - Class 4 Maths (Decimals)?
To plot a decimal on a number line:
- Identify the two whole numbers the decimal lies between.
- Divide that segment into 10 equal parts (each part = 0.1).
- Count the required number of parts from the left whole number.
For example, 2.3 lies between 2 and 3. Divide the segment into 10 parts and count 3 parts from 2.
Solved Examples
Example 1: Example 1: Plot 0.4 on a Number Line
Problem: Show 0.4 on a number line from 0 to 1.
Solution:
Step 1: 0.4 lies between 0 and 1.
Step 2: Divide the segment into 10 equal parts.
Step 3: Count 4 parts from 0.
0 — 0.1 — 0.2 — 0.3 — 0.4 — 0.5 — 0.6 — 0.7 — 0.8 — 0.9 — 1
Answer: 0.4 is the 4th mark from 0.
Example 2: Example 2: Plot 1.7 on a Number Line
Problem: Show 1.7 on a number line from 1 to 2.
Solution:
Step 1: 1.7 lies between 1 and 2.
Step 2: Divide into 10 equal parts. Count 7 parts from 1.
1.0 — 1.1 — 1.2 — 1.3 — 1.4 — 1.5 — 1.6 — 1.7 — 1.8 — 1.9 — 2.0
Answer: 1.7 is the 7th mark from 1.
Example 3: Example 3: Read a Decimal from a Number Line
Problem: A point is at the 6th mark on a number line from 3 to 4 (divided into 10 parts). What decimal does it represent?
Solution:
Step 1: Each part = 0.1.
Step 2: 6th mark from 3 = 3 + 6 × 0.1 = 3 + 0.6 = 3.6.
Answer: The point represents 3.6.
Example 4: Example 4: Plot 0.5 (Show it Equals 1/2)
Problem: Plot 0.5 on a number line from 0 to 1. What fraction is this?
Solution:
Step 1: 0.5 is at the 5th mark out of 10 from 0.
Step 2: This is exactly at the midpoint between 0 and 1.
Step 3: 0.5 = 5/10 = 1/2.
Answer: 0.5 is at the middle of the number line, equal to 1/2.
Example 5: Example 5: Compare Decimals on Number Line
Problem: Plot 0.3 and 0.7 on the same number line. Which is greater?
Solution:
0 — 0.1 — 0.2 — 0.3 — 0.4 — 0.5 — 0.6 — 0.7 — 0.8 — 0.9 — 1
Step 1: 0.7 is farther to the right than 0.3.
Answer: 0.7 > 0.3. Numbers farther to the right are greater.
Example 6: Example 6: Plot a Decimal Between Two Tenths
Problem: Plot 2.35 on a number line.
Solution:
Step 1: 2.35 lies between 2.3 and 2.4.
Step 2: Divide the segment from 2.3 to 2.4 into 10 parts (each part = 0.01).
Step 3: 2.35 is at the 5th mark — exactly halfway between 2.3 and 2.4.
Answer: 2.35 is halfway between 2.3 and 2.4.
Example 7: Example 7: Find the Decimal Between Two Points
Problem: What decimal is exactly halfway between 0.2 and 0.3?
Solution:
Step 1: Halfway = (0.2 + 0.3) ÷ 2 = 0.5 ÷ 2 = 0.25.
Answer: 0.25 is exactly halfway between 0.2 and 0.3.
Example 8: Example 8: Word Problem
Problem: Ria ran 1.3 km and Aman ran 1.8 km. Show both distances on a number line from 1 to 2. Who ran more?
Solution:
1.0 — 1.1 — 1.2 — R(1.3) — 1.4 — 1.5 — 1.6 — 1.7 — A(1.8) — 1.9 — 2.0
Aman's point (1.8) is farther right.
Answer: Aman ran more (1.8 km > 1.3 km).
Example 9: Example 9: Identify Missing Decimals
Problem: Fill in the missing decimals: 4.1, ___, 4.3, ___, 4.5
Solution:
Step 1: The pattern increases by 0.1.
Step 2: Missing values: 4.1, 4.2, 4.3, 4.4, 4.5.
Answer: 4.1, 4.2, 4.3, 4.4, 4.5
Key Points to Remember
- Decimals can be shown on a number line by dividing the space between whole numbers into 10 equal parts.
- Each part between whole numbers equals 0.1 (one tenth).
- A decimal farther to the right on the number line is greater.
- 0.5 is always at the midpoint between two consecutive whole numbers.
- For hundredths, divide each tenth into 10 more parts (each = 0.01).
- Number lines help compare and order decimals visually.
Practice Problems
- Plot 0.8 on a number line from 0 to 1.
- Plot 3.2 and 3.9 on a number line from 3 to 4. Which is greater?
- A point is at the 4th mark on a number line from 5 to 6 (divided into 10 parts). What decimal is it?
- What decimal is exactly halfway between 1.0 and 2.0?
- Fill in: 2.5, ___, 2.7, ___, 2.9.
- Where would 0.25 fall on a number line between 0 and 1?
- Neha walked 2.4 km and Dev walked 2.6 km. Show on a number line and tell who walked more.
Frequently Asked Questions
Q1. How do you plot a decimal on a number line?
First find which two whole numbers the decimal lies between. Then divide that segment into 10 equal parts (each = 0.1). Count the correct number of parts from the left whole number.
Q2. How many parts should the number line be divided into?
For tenths, divide into 10 equal parts. For hundredths, divide each tenth section into 10 more parts (100 parts total between whole numbers).
Q3. Which decimal is farther right on a number line?
The greater decimal is farther to the right. For example, 0.8 is to the right of 0.3, so 0.8 > 0.3.
Q4. Where is 0.5 on a number line?
0.5 is exactly at the midpoint between 0 and 1 (or between any whole number n and n+1, it would be n.5). It is the same as 1/2.
Q5. Can you plot hundredths on a number line?
Yes. To plot hundredths like 0.25, zoom in between 0.2 and 0.3, divide that segment into 10 parts, and count 5 parts from 0.2.
Q6. How do number lines help with decimals?
They provide a visual representation that makes it easy to compare decimals, understand their order, and see how close or far apart they are.
Q7. What if a decimal falls exactly on a whole number?
Decimals like 1.0, 2.0, 3.0 fall exactly on the whole number marks. 1.0 = 1, 2.0 = 2, and so on.
Q8. How do you find the decimal between two given decimals?
Add the two decimals and divide by 2. For example, the decimal between 0.4 and 0.6 is (0.4 + 0.6) / 2 = 0.5.
Q9. Is this topic in the NCERT Class 4 syllabus?
Yes. Plotting decimals on a number line is part of the Decimals chapter in Class 4 NCERT Maths. It helps students build a visual understanding of decimal values.
