While what you did is correct given XL's rules of operator precedence,
the OP meant ^(n*2). The formula s/he started with calculates the
final amount A given a principal P compounded at a periodic rate of i
over n periods with compounding occuring every t intervals (where n/t
is an integer). Then, A=P(1+i/t)^(n*t)

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
says...
But what has that got to do with Excel?

This is a paper exercise. Start with

A=P(1+i/2)^n*2 = A/P=(1+i/2)^n*2 = A/2P=(1+i/2)^n = (A/2P)^(1/n)=1+i/2
etc

Just follow the same steps for the second equation.