49. Assertion: The unit digit of cube of 128, 38 and 48 is 4.

Question

Reason: If a number ends with 8, then its cube ends with 2.

Answer 1

To evaluate the assertion and reason, let's analyze the units digit of the cubes of the numbers given:

1. 128: The unit digit is 8.

   • The cube of a number that ends in 8 (like 8) is calculated as follows: \(8^3 = 512\) which ends in 2.

2. 38: The unit digit is also 8.

   • Again, \(8^3 = 512\) which ends in 2.

3. 48: The unit digit is again 8.

   • Similarly, \(8^3 = 512\) which ends in 2.

Now, none of these numbers (128, 38, and 48) have cubes that end in 4; in fact, they all end in 2.

Thus, the Assertion is false because the unit digit of the cube of each of these numbers is not 4.

Now, examining the Reason: The statement "If a number ends with 8, then its cube ends with 2" is true.

Therefore, the final evaluation is:

• The Assertion is false.
• The Reason is true.

In conclusion, the answer would be that the assertion is incorrect, but the reasoning is correct.