A Friday finish this week: I finished this week’s Listener puzzle, “The X-factor”, a little after 11 pm. It’s a numerical and an ingenious one with a lot of subtle deductions to be made along the way. Very tough at first — I think after my lunch hour I’d identified the value of one letter and filled one cell in the grid. But the pace picked up steadily as I chipped more and more of it away and I must have filled in the last quarter or so of the grid in under fifteen minutes.