what will be the sum of adding all the possible 4 digit numbers formed by 7,9,1,3 using each of the digits only once ?
options are:
133220
133230
122320
133320
Answers
Answered by
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Since it's a 4 digit number, each digit will appear 6=24/4 times in each of units, tens, hundreds, and thousands place. Therefore, the sum of digits in the units place is 6(7+9+1+3)=120.
Similarly sum of digits at tens, hundreds, thousand place is 120.
Required sum of all numbers =
120+120.10+120.100+130.1000 = 133320
Therefore answer is 133320.
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