Not only have they stripped out food and energy but the Clinton revision to the CPI made in the early 90’s dramatically changed even the so-called core inflation numbers. Real world inflation right now is much closer to 10% than the bogus numbers being reported. I think shadowstats.com which uses the pre Clinton CPI formula for comparison tells the real story.
He doesn't use any formula. He takes the current number and adds some fixed percentage. He's selling subscriptions after all.