Question

What is the next number of the following sequence 27, 54, 81, 135, 189, ?

Answer 1

Here, each number in the series is being increased by 27.

27, 54 - 

here, 27 + 27 = 54


54, 81 -

here, 27 + 54 = 81

so, and so....

therefore, 
at the end - 

, 135, 189, ?

it will be = 27 + 189 = 216

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The next number in the series will be 126.

Answer 2

27+27=54,54+27=81,81+54=135,135+54=189,189+81=270