A Regular SeriesSeries teasers are where you try to complete the sequence of a series of letters, numbers or objects.
What number comes next in this series? The decimals are rounded to 4 places.
60, 90, 108, 120, 128.5714, 135, 140, 144, 147.2727, ?
What do these numbers represent?
HintTry this angle: divide each number by 180.
AnswerThe next number is 150.
The formula is 180(n-2)/n, starting with n=3 for the first term.
These numbers are the size (in degrees) of the interior angles in a regular n-sided polygon. An equilateral triangle has three 60 degree angles, a square has four 90 degree angles, a regular pentagon has five 108 degree angles, and so on. A regular dodecagon has twelve 150 degree angles.
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