title: Using floorf to reduce the number of decimals
body: <p>I would like to use the first five digits of a number for computation.
  For example,
  A floating point number: 4.23654897E-05</p>
  
  <p>I wish to use 4.2365E-05.I tried the following </p>
  
  <pre><code>#include &lt;math.h&gt;
  #include &lt;stdio.h&gt;
  
  float num = 4.23654897E-05;
  int main(){
  float rounded_down = floorf(num * 10000) / 10000;
  printf("%f",rounded_down);
  return 0;
  
  }
  </code></pre>
  
  <p>The output is 0.000000.The desired output is 4.2365E-05.
  In short,say 52 bits are allocated for storing the mantissa.Is there a way to reduce the number of bits being allocated?</p>
  
  <p>Any suggestions on how this can be done?</p>