Taking the figures at face value, Sony was selling (or at least manufacturing) an average of 28,000 readers per month (I took 70,000 units as the average sold per month and then 40% of that). Using this monthly rate, the annual sales of the Sony Reader are at nearly 350,000 units. Using the same formula, Amazon is ordering an average of 42,000 units per month, which will add up to over 500,000 units sold this year.[...]
Makes sense to me if I follow the writers' logic.
What's more interesting is finally getting closer to some real hard numbers on the number of e-reading devices sold.