Find the digit in the unit's place of $$124^\text{n}+124^\text{n+1}$$​, where n is any whole number.

Correct option is A

Given:

Expression: 1$$24^n + 124^{n+1},$$​ where n is any whole number

Concept Used:

​$$124^n$$ will have unit digit 4 if n is odd, and 6 if n is even

​$$124^{n+1}$$ will have unit digit 6 if n is odd, and 4 if n is even​

Solution:​

Let’s test both cases:

Case 1: n is even
$$124^n \to 6, 124^{n+1} \to 4$$​

6 + 4 = 10

Unit digit = 0

Case 2: n is odd
$$124^n \to 4,\quad 124^{n+1} \to 6$$​

4 + 6 = 10

Unit digit = 0

In both cases, unit digit = 0