John drinks a bottle of water every half hour.  A normal sudoku puzzle takes him 45 minutes.  An extreme sudoku takes 4 times that long.  How many bottles of water does he drink in that time?
He drinks a bottle of water every 60/2=
<gadget id="calculator">60/2</gadget>
<output>30</output>
30 minutes.
It takes him 45*4=
<gadget id="calculator">45*4</gadget>
<output>180</output>
180 minutes to solve an extreme sudoku.
So he drinks 180/30=
<gadget id="calculator">180/30</gadget>
<output>6</output>
6 bottles in that time.

<result>6</result>