NCERT Solutions
Class 10 - Mathematics - Chapter 1: REAL NUMBERS - EXERCISE 1.1
Question 5

Question. 5

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

Answer:

\(6^n\) cannot end with 0 because it always ends with 6 for all natural numbers \(n\).

Detailed Answer with Explanation:

We are asked to check whether the number \(6^n\) can ever end with the digit 0, where \(n\) is any natural number.

Step 1: Understand what it means for a number to end with 0

If a number ends with 0, it must be divisible by 10.

Being divisible by 10 means the number must contain both prime factors:

\(2\) and \(5\)

This is because:

\(10 = 2 \times 5\)

So, for \(6^n\) to end in 0, the number must include the factor 5.

Step 2: Look at the structure of \(6^n\)

We know:

\(6 = 2 \times 3\)

So,

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

Using exponents, this becomes:

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

Step 3: Check whether any power of 6 contains the factor 5

The prime factors in \(6^n\) are only \(2\) and \(3\).

There is no factor of \(5\) in \(6^n\) for any natural number \(n\).

Since a factor 5 never appears, \(6^n\) can never be divisible by 10.

Step 4: Observe the last digit pattern of powers of 6

Let us check the first few powers:

\(6^1 = 6\)

\(6^2 = 36\)

\(6^3 = 216\)

\(6^4 = 1296\)

In each case, the last digit is 6.

This pattern continues for every higher power because multiplying a number ending in 6 by 6 again always gives a number ending in 6.

Step 5: Conclude the result

Since no power of 6 contains the factor 5, \(6^n\) can never be divisible by 10 and therefore cannot end with 0.

Thus:

\(6^n\) never ends with 0 for any natural number \(n\).

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