&   &   &     & =     \\
  &  \frac{1}{5 \times 10^{3}} = &   &   &     & =   \\
  &  \frac{1}{5 \times 10^{5}} = &   &   &     & =
\end{array}$\

Exercise 2.3 shows that the square of a fraction means “taking a fraction of a fraction". If the fraction is a very small number then its square may be very small indeed. How small must the number be so that the square “is as good as" zero? In other words, how small is a dibbl? This is a profound question. It suffices to say for now that a dibbl is not an ordinary number, but is something that is smaller than any fraction!

We close this subsection by reminding ourselves why it is difficult to assign a value to $\frac{1}{0}$.

[**EXERCISE**]{}

[**2.5**]{}\
(a) Ask your calculator to find a value for $\frac{1}{0}$, and write down the result. If you got a value, you are finished.\
(b) If your calculator couldn’t do the problem try dividing $1$ by a lot of values in the denominator that are close to zero. Then you can try to guess the result. One way to do this is to take a sheet of graph paper, and plot 