- A312
- B3125
- C120
- D216
View written solutionFree
Correct answer: D
- Condition for divisibility by 3
A number is divisible by if the sum of its digits is divisible by .
We must form a 5-digit number using digits from without repetition.
So we choose any 5 digits out of these 6.
The sum of all six digits is which is divisible by .
If one digit is omitted, then the sum of the chosen 5 digits is For divisibility by : Since , we need So the omitted digit must be one of .
Thus there are only 2 valid sets of 5 digits:
- omit : digits
- omit : digits
- Count numbers for each valid set
Case 1: Omit
Digits are .
All 5 digits are nonzero, so every permutation gives a valid 5-digit number.
Number of such numbers:
Case 2: Omit
Digits are .
Total permutations of these 5 digits:
But those starting with are not 5-digit numbers. Fix in the first place, and arrange the remaining 4 digits:
So valid 5-digit numbers in this case:
- Total count
Therefore, total numbers divisible by are
- Option check
The correct option is: So Option D is correct.
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