Compound interest

FV = P(1+r/n)nt

P=1 t
10 20 30
     r      5%
n=1:

n=10:

n→∞:
 
n=1:

n=10:

n→∞:
 
n=1:

n=10:

n→∞:
 
10%
n=1:

n=10:

n→∞:
 
n=1:

n=10:

n→∞:
 
n=1:

n=10:

n→∞:
 

Using 1 for P makes all the results multiples of P, the starting principle, whatever it is.
FV = (1+r/n)nt

When n→∞, FV = Pert

When n=1, FV simplifies to P(1+r)t