You’re reading Significant Digits, a daily digest of the numbers tucked inside the news.

0.04 percent

Percentage of ad impressions that were billed incorrectly on Facebook as part of a bug that meant advertisers were overcharged. That seems small, and on the whole it is, but Facebook’s ad revenue hit nearly $8 billion last quarter, so even a tiny fraction of its ad impressions is a decent chunk of the internet. The company is offering refunds to affected advertisers. [CNN]

5.3 percent

A PwC study analyzing CEO changes at the 2,500 largest public companies in the world found that ethical lapses leading to dismissal were responsible for 5.3 percent of CEO turnover in 2012 to 2016, up more than a percentage point from the rate in 2007 to 2011. [PwC]

9 seasons

Bobby Moynihan, the second-longest-tenured current cast member of “Saturday Night Live,” will leave the show after Saturday’s season finale. He’s landed a sitcom over at CBS for the fall. [Variety]

20 percent

North American tree populations are moving westward. Scientists think that 20 percent of the observations in their study of the trend are explainable by changes in precipitation tied to climate change — but that other 80 percent of the reason trees are fleeing the coast? There are still a bunch of questions. [The Atlantic]

128 blood tests

Certain lead tests from Magellan Diagnostics can provide inaccurate blood lead levels, government agencies said Wednesday. In Flint, Michigan, which has had serious problems with the presence of lead in the water, 128 tests were done with the potentially faulty Magellan kits. [MLive]

$19 million

Cheddar, a financial news streaming service startup, pulled in $19 million in funding to a valuation of $85 million. [Talking Biz News]

If you see a significant digit in the wild, send it to @WaltHickey.