9thnonagonalnumber

<-- Enter nonagonal number statement
  

Calculate nonagonal number 9

The formula for nonagonal number n is as follows
Nn  =  n(7n - 5)
  2

Given n = 9, we have:
N9  =  9(7(9) - 5)
  2

N9  =  9(63 - 5)
  2

N9  =  9(58)
  2

N9  =  522
  2

N9 = 261