title: How many operations can we do with an 8-digit (plus decimal) calculator?
body: <p>I have this model: a simple 8-digit display calculator (no memory buttons, no square root etc etc) has buttons (the decimal point does not count as a 'digit'):
  10 buttons for integers 0 to 9, 
  1 button for dot (decimal point, so it can hold decimals, like from 0.0000001 to 9999999.9), 
  4 buttons for operations (+, -, /, *), and 
  1 button for equality (=). (the on/off button doesn't count for this question)</p>
  
  <p>The question is two-fold: how many numbers can they be represented on the calculator's screen? (a math-explained solution would be appreciated)
  *AND
  if we have to make all 4 basic operations between <em>any</em> pair of 2 numbers, of the above calculated, how many operations would that be?</p>
  
  <p>Thank you for your insight and help!</p>