Engineering Board Exam Reviewer · Number & Digit Problems · hard
Find the sum of all 3-digit numbers that can be formed using the digits 1, 2, and 3, each exactly once.
- 1332
- 666
- 2664
- 1998
Answer
A. 1332
Solution
Each digit appears in each place value 2 times (there are 3!=6 numbers). The sum is 2(1+2+3)(100+10+1)=2(6)(111)=1332.
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