CDS
Government Jobs Exams
Logical Reasoning
Number Series
What are the next three numbers in this series?
4, 6, 12, 18, 30, 42, 60, 72, 102, 108, ?, ?, ?
Read Solution (Total 3)
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- The next three numbers are 108,138,150
Subtract 1 from each numbers in the series, we get
3,5,11,17,29,41,59,71,101,....which are prime numbers.
Add 1 to each numbers to get this series, 5,7,13,19,31,43,61,73,103,.....
We see that only those un-prime numbers are taken which are mean of two prime numbers.(for e.g 72 is the mean of 71 and 73). Un-prime number 24 is not taken because it is between 23 (prime) and 25 (un-prime).
The prime numbers after 103 are 107,109,113,127,131, 137,139,149,151,157,163,167,173,179,181,… etc.
From here we see 108, 138 and 150 are three numbers which are mean of two prime numbers.
So the next three numbers are 108,138,150
Good question, thanks. - 12 years agoHelpfull: Yes(19) No(1)
- due to seems that pattern followed of prime numbers when substracted 1 from that so the next numbers be 137+1,139+1,
- 12 years agoHelpfull: Yes(2) No(5)
- ans:138,150,180
process is 2k+1,2k+3...
- 12 years agoHelpfull: Yes(1) No(3)
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