So, this is untrue.

Surprising, I know: President Trump making an untrue claim on Twitter. In this case, though, the falsehood about viewership is incontrovertible, lacking any of the wiggle room that generally cushions Trump’s statements. Trump is citing a number from Nielsen, a company that also reports that President Barack Obama’s first State of the Union address in 2010 had 48 million viewers. We’re comparing apples to apples, and Trump’s apple is just a bit smaller than his predecessor’s.

One might wonder why Trump would make an assertion that’s so easy to demonstrate as untrue. But the explanation for why he does so also comes easily. Trump is misrepresenting his ratings because Trump — who loves using numbers as a way of bolstering his exaggerations — has been misrepresenting his television ratings as exceptional for years and years.

There are three sets of numbers that have been favorites of Trump’s over the past decade: television ratings, polls and stock prices. He has mastered the art of cherry-picking and sharing good numbers while mostly ignoring negative numbers, the way a guy selling you a house would emphasize and exaggerate the good things about it while skipping over the fact that the wood floors are termite-infested.

The first Trump tweet about any of these subjects in the Twitter era came in May 2010.

That season of “Celebrity Apprentice” was the show’s third. It averaged 7.4 million viewers, down from 9 million the season before, though the finale did slightly better. This was already well after ratings for the “Apprentice” franchise had started to slide, as we noted last year when assessing Trump’s repeated claims that the show was a ratings smash.

Only one week was any “Apprentice” show ever the No. 1 show in America: the finale of the first season of the original series. That didn’t stop Trump from trumping up fake Time magazine covers declaring the show to be a “television smash” — and then sprinkling those fake covers throughout his properties.

The Post’s Marc Fisher explores how President Trump’s concerns with numbers and ratings have shaped his career. (Bastien Inzaurralde/The Washington Post)

Over the next few years, Trump tweeted more about ratings than polls or stocks, thanks largely to “Celebrity Apprentice” still being on air. He did also start demonstrating one of his other favorite uses of numbers on Twitter: tweeting about bad ratings as a cudgel against those he disliked. To wit:

In 2012, Trump tweeted about political polls with some regularity as his public advocacy for Mitt Romney’s presidential candidacy seemed mostly to consist of tweets about how Romney was doing and what the polls showed. He also tweeted more about the stock markets in 2012, often for political reasons …

… but not always …

Then he threw his hat into the ring for the Republican nomination. By mid-July 2015, he was leading the Republican field, and his tweets about poll numbers soared. In October 2015, he tweeted about poll numbers 73 times, more than twice a day on average. That lasted until February of the next year, as he started to lock up the Republican nomination. Then he shifted into general election mode, and he slipped into second place in national polling behind Hillary Clinton. His tweets about polling tapered off.

Closer to Election Day, he began tweeting about polls again, usually either state polls showing him doing well or sketchy online polls after the presidential debates.

Once he was inaugurated, the polls got worse. So he turned back to stock prices, instead. Since his inauguration, he has  mentioned “stock” or “market” 65 times on Twitter, more than twice as often as he’s mentioned polls. He looks for positive news where he can find it — like the guy selling real estate who notes the refurbished kitchen and not the leaking septic tank.

For Trump, numbers aren’t really measurements of tangible reality. They are bits of flair to be worn and shown off, or they are things to be ignored. They are potential elements of a sales pitch. And sales pitches aren’t meant to be accurate; they’re meant to sell.

How will Trump respond to having it pointed out that his tweet was wrong? The same way a guy who sold you a house would respond when the floor rotted through.