A -digit number is divisible by . Which digit can replace ?
- A1
- B2
- C3
- D4
Solution & Step-by-step Explanation
For a number to be divisible by , it must be completely divisible by both and ().
1. Divisibility rule of 4: The last two digits must be divisible by . Here, the last two digits are . The choices for an even digit could be to make numbers like divisible by .
2. Divisibility rule of 11: The difference between the sum of digits at odd positions and the sum of digits at even positions must be either or a multiple of .
* Sum of digits at odd positions (1st, 3rd, 5th)
* Sum of digits at even positions (2nd, 4th)
Difference
For this difference to be a multiple of , we set:
Since satisfies both the divisibility conditions (the last two digits are divisible by ), the correct option is .
1. Divisibility rule of 4: The last two digits must be divisible by . Here, the last two digits are . The choices for an even digit could be to make numbers like divisible by .
2. Divisibility rule of 11: The difference between the sum of digits at odd positions and the sum of digits at even positions must be either or a multiple of .
* Sum of digits at odd positions (1st, 3rd, 5th)
* Sum of digits at even positions (2nd, 4th)
Difference
For this difference to be a multiple of , we set:
Since satisfies both the divisibility conditions (the last two digits are divisible by ), the correct option is .