Calculating: per-share investments and pre-tax earnings

[orion]

I'm sorry if this has been discussed here before (searched but didn't find anything).

 

In Buffett's latest letters he gives hints on how to value BRK. So for example here on page 7 ( http://www.berkshirehathaway.com/letters/2013ltr.pdf ) he gives an update of the "two quantitative factors": per-share investments and pre-tax earnings.

 

When trying to calculate these numbers myself, I just can't get them right. Does anybody have a link or can give some hints?

 

Thanks