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Q: What is the sum of all 3 digits number that can be formed using digits 0,1,2,3,4,5 with no repitition ?

  • 1
    28450
  • 2
    26340
  • 3
    32640
  • 4
    36450
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Answer : 3. "32640"
Explanation :

Answer: C) 32640 Explanation: We know that zero can't be in hundreds place. But let's assume that our number could start with zero.   The formula to find sum of all numbers in a permutation is   111 x no of ways numbers can be formed for a number at given position x sum of all given digits   No of 1 s depends on number of digits   So,the answer us   111 x 20 x (0+1+2+3+4+5) = 33300   We got 20 as follows. If we have 0 in units place we can form a number in 4*5 ways. This is for all numbers. So we have substituted 20 in formula.   Now, this is not the final answer because we have included 0 in hundreds place. so we have to remove the sum of all numbers that starts with 0.   This is nothing but the sum of all 2 digits numbers formed by 1 2 3 4 5. Because 0 at first place makes it a 2 digit number.   So the sum for this is 11 x 4 x (1+2+3+4+5). =660   Hope u understood why we use 4. Each number can be formed in 4x1 ways   So, the final answer is 33300-660 = 32640

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