Math Puzzle of the Day…

Published on 2004-10-01 by Mark VandeWettering

Consider all the powers of 2: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, and so on…

The unit digits follow the progression 1, 2, 4, 8, 6, 2, 4, 8, 6, 2, 4, 8, 6… Nothing too amazing, a nice cyclic relationship, and except for the priming 1, all evenly distributed. But consider the leading digit. In the limit, what are the distribution of the leading digits? I computed a table:

  <th>
    Percentage
  </th>
</tr>

<tr>
  <td>
    1
  </td>
  
  <td>
    0.3010299956639812
  </td>
</tr>

<tr>
  <td>
    2
  </td>
  
  <td>
    0.17609125905568124
  </td>
</tr>

<tr>
  <td>
    3
  </td>
  
  <td>
    0.12493873660829996
  </td>
</tr>

<tr>
  <td>
    4
  </td>
  
  <td>
    0.096910013008056461
  </td>
</tr>

<tr>
  <td>
    5
  </td>
  
  <td>
    0.079181246047624776
  </td>
</tr>

<tr>
  <td>
    6
  </td>
  
  <td>
    0.066946789630613179
  </td>
</tr>

<tr>
  <td>
    7
  </td>
  
  <td>
    0.057991946977686726
  </td>
</tr>

<tr>
  <td>
    8
  </td>
  
  <td>
    0.051152522447381332
  </td>
</tr>

<tr>
  <td>
    9
  </td>
  
  <td>
    0.045757490560675129
  </td>
</tr>
Leading Digit

The puzzle is to verify and to explain this distribution. Neat stuff.