Chapter 1: Real Numbers (Exercise 1.4)
Topic: Visualising Real Numbers on the Number Line through Successive Magnification
Question 1:
Visualise $2.874$ on the number line using successive magnification.
Solution:
Step 1: The number $2.874$ lies between $2$ and $3$.
Divide the portion of the number line between $2$ and $3$ into $10$ equal parts.
Locate the interval between $2.8$ and $2.9$.
Step 2: The number $2.874$ lies between $2.8$ and $2.9$.
Magnify the interval $[2.8, 2.9]$ and divide it into $10$ equal parts ($2.81, 2.82, \dots, 2.89$).
Locate the interval between $2.87$ and $2.88$.
Step 3: The number $2.874$ lies between $2.87$ and $2.88$.
Magnify the interval $[2.87, 2.88]$ and divide it into $10$ equal parts ($2.871, 2.872, \dots, 2.879$).
The $4^{\text{th}}$ mark after $2.87$ represents the exact location of $2.874$.
Question 2:
Visualise $5.\overline{28}$ ($5.2828...$) on the number line up to $4$ decimal places (i.e., $5.2828$).
Solution:
Step 1: The number $5.2828$ lies between $5$ and $6$.
Divide the segment between $5$ and $6$ into $10$ equal parts.
Identify the interval between $5.2$ and $5.3$.
Step 2: Magnify the interval $[5.2, 5.3]$ and divide it into $10$ equal parts.
Identify the interval between $5.28$ and $5.29$.
Step 3: Magnify the interval $[5.28, 5.29]$ and divide it into $10$ equal parts.
Identify the interval between $5.282$ and $5.283$.
Step 4: Magnify the interval $[5.282, 5.283]$ and divide it into $10$ equal parts ($5.2821, 5.2822, \dots, 5.2829$).
The $8^{\text{th}}$ mark after $5.282$ accurately represents $5.2828$.