Which of the numbers given below is exactly divisible by 24?
- A14744
- B28856
- C43976
- D57528
Solution & Step-by-step Explanation
A number is exactly divisible by if it is co-prime divisible by both and ().
1. Divisibility rule for 8: The last three digits of the number must form a number divisible by .
2. Divisibility rule for 3: The sum of all digits of the number must be a multiple of .
Let's test each option:
* Option A: 14744
* Last digits: . Since , it is divisible by .
* Sum of digits: . Since is not a multiple of , is not divisible by .
* Option B: 28856
* Last digits: . Since , it is divisible by .
* Sum of digits: . Since is not divisible by , is not divisible by .
* Option C: 43976
* Last digits: . Since , it is divisible by .
* Sum of digits: . Not a multiple of , so it is not divisible by .
* Option D: 57528
* Last digits: . Since , it is divisible by .
* Sum of digits: . Since is a multiple of (), it is divisible by .
Since satisfies both divisibility rules, it is completely divisible by .
Verification: .
1. Divisibility rule for 8: The last three digits of the number must form a number divisible by .
2. Divisibility rule for 3: The sum of all digits of the number must be a multiple of .
Let's test each option:
* Option A: 14744
* Last digits: . Since , it is divisible by .
* Sum of digits: . Since is not a multiple of , is not divisible by .
* Option B: 28856
* Last digits: . Since , it is divisible by .
* Sum of digits: . Since is not divisible by , is not divisible by .
* Option C: 43976
* Last digits: . Since , it is divisible by .
* Sum of digits: . Not a multiple of , so it is not divisible by .
* Option D: 57528
* Last digits: . Since , it is divisible by .
* Sum of digits: . Since is a multiple of (), it is divisible by .
Since satisfies both divisibility rules, it is completely divisible by .
Verification: .