Sudoku

My husband likes to do the Sudoku puzzles in the Daily Telegraph every day.
He takes out the relevant pages and folds them up into a small square.
Moderate, Gentle or Killer Sudoku, he has a crack at them all.
If they prove to be tricky, he sighs and grips the paper a little tighter.
He uses a special pencil with a rubber on the end.
It is a very serious business!