4thnonagonalnumber

<-- Enter nonagonal number statement
  

Calculate nonagonal number 4

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

Given n = 4, we have:
N4  =  4(7(4) - 5)
  2

N4  =  4(28 - 5)
  2

N4  =  4(23)
  2

N4  =  92
  2

N4 = 46