In the first math exam we got this example:

What is the limit of this serie: (the calculator use not was allowable!)

an=(1+1/(2^n+1))^(2^(n+1)) where n->infinity (n is integer)

the limit is e^2 (~7.39), but look, what happen if we try to calculate it! Grab your 48, and plot it: 0 40 XRNG 0 10 YRNG 'n' INDEP ERASE DRAW You'll see, the value of function about 37.5-37.8 will be 1. (not 7.39)

That happen, when 1+1/(2^n+1)=1 for 12 digit, the limit will be 1.

Where? Its simple calculable:

1/(2^n+1)<5e-12 -> n>37.54

Csaba