NCERT Class X Chapter 1: Real Numbers Exercise 1.1 Question 5

NCERT Class X Chapter 1: Real Numbers Exercise 1.1 Question 5

Question:

Check whether \( 6^n \) can end with the digit 0 for any natural number \( n \).

Given:

The expression \( 6^n \), where \( n \) is a natural number.

To Find:

Whether \( 6^n \) can end with the digit 0 for any natural number \( n \).

Formula:

To end with 0, a number must be divisible by 10.
\( 10 = 2 \times 5 \)

Solution:

Step 1: For a number to end with 0, it must be divisible by 10.
The prime factorization of 10 is \( 10 = 2 \times 5 \).

$$ 10 = 2 \times 5 $$

Step 2: Write 6 as a product of its prime factors.

$$ 6 = 2 \times 3 $$

Step 3: Raise both sides to the power \( n \).

$$ 6^n = (2 \times 3)^n $$

Step 4: Apply the exponent rule: \( (a \times b)^n = a^n \times b^n \).

$$ 6^n = 2^n \times 3^n $$

Step 5: Observe the prime factors of \( 6^n \).
The only prime factors are 2 and 3 (each raised to the power \( n \)).
There is no factor of 5 in \( 6^n \) for any natural number \( n \).

Step 6: Since \( 6^n \) does not contain a factor of 5, it cannot be divisible by 10.
Therefore, \( 6^n \) cannot end with the digit 0 for any natural number \( n \).

Result:

No, \( 6^n \) cannot end with the digit 0 for any natural number \( n \).

Reason: Its prime factorization is \( 2^n \times 3^n \), which never includes a factor of 5, so it cannot be divisible by 10.

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