For Donald J. Trump the TV star, ratings were made to be embellished. This turns out to be true as well of Donald J. Trump the president.

Mr. Trump spent his first weekend in office at war with math. He said on Saturday that his inauguration crowd — which photographs showed was dwarfed by Barack Obama’s estimated 1.8 million in 2009 — “looked like a million, a million and a half.” His staff members backed up that claim with what his adviser Kellyanne Conway memorably termed “alternative facts.”

For the political news media, the brazenness was stunning. But those of us who cover television have seen this kind of thing before: the inventions of a celebrity, surrounded by yes men and women, who creates his own reality.

We recognize it because, not so long ago, that celebrity was Donald J. Trump.

Mr. Trump has a reputation among TV reporters for using his own bespoke numbers. In 2015, he came to a Television Critics Association panel for his final season hosting “The Celebrity Apprentice” and declared it “the Number 1 show on television.”