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有个sequence S1, S2, S3,....,Sn, 然后Sn = 2Sn-1, if no number in this sequence is a multiple of 100, then S1 could be which of the following? (多重选)Answers are: 5, 10,15, 20, 30, 40, 50
It is interesting to see this...
Sn=2^(n-1)*S1
100=5*5*2*2
Thus for the condition that there is no number equal to 100*x, then we cannot include two 5's in this process.
Answer: 5, 10, 15, 20, 30, 40
Thanks for your questions. |
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