Book value does not work for tech companies like microsoft. The world has changed since Benjamin Graham. In his time, it was all industrial.
Microsoft does a lot of R&D and has a ton of patents. They are not in the book value. Their source code is not in the book value. Book values for all tech companies are quite skewed - even for companies like Intel that operate large very expensive chip factories because they also do not show part of their value.
On Genjamin Graham's times companies were industrial and very little value was on intellectual property. ALSO: stocks where a lot cheaper.
Generally Tech companies are more valued by cash flow and earnings potential (current year, next year projected earning) and not by book value.