Number Puzzle #133
Find the missing number in the series
1,20,?,266,675
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Number Puzzle #133 1,20,?,266,675
(4 votes, average: 3.50 out of 5) (4 votes, average: 3.50 out of 5) (4 votes, average: 3.50 out of 5) (4 votes, average: 3.50 out of 5)
The series is
1,20,x,266,675
taking difference of adjacent terms
19,x−20,266−x,409
taking difference of adjacent terms again
x−39,286−2x,143+x
taking difference of adjacent terms again
325−3x,3x−143
taking difference of adjacent terms again
6x−468
Let this be zero so 6x−468=0 or x=78
78