What happened?
Ukrainian President Volodymyr Zelenskyy on Sunday gave a rare official military death toll, two years after Russian President Vladimir Putin launched his full-scale invasion.

Who said what?
Roughly "31,000 Ukrainian military personnel have been killed in this war," Zelenskyy said. "Not 300,000, not 150,000, not whatever Putin and his deceitful circle have been lying about. But nevertheless, each of these losses is a great sacrifice for us." He put Russia's losses at 180,000 killed and 320,000 injured.

The commentary
Kyiv "keeps casualty figures closely guarded so as to not dampen public morale" or give Russia information on troop strength, The Washington Post said. U.S. officials "put the losses much higher," The New York Times said, estimating at least 70,000 Ukrainians have been killed, with Russia's casualties "about twice as high."

What next?
Zelenskyy said Ukraine's fate depends on Western aid, and "we will not lose this war if we get the weapons." President Joe Biden will press congressional leaders Tuesday to send him a Senate-approved aid bill with $60 billion for Ukraine.

What happened?
We get a bonus day this week — not a holiday, but a 29th day in February, as happens every leap year.

How we got here
Julius Caesar, "dealing with major seasonal drift" in Roman calendars, introduced the Julian calendar in 46 BCE, counting a year as 365.25 days and adding an extra day every four years, The Associated Press said. But a year is actually 365.242 days, so Pope Gregory XIII knocked out a leap year every hundred years — except years divisible by 400, like 2000. The 1582 Gregorian calendar "remains in use today" and, while its "gnarly math" is not perfect, it reduced "drift to mere seconds."

The commentary
"Without the leap years, after a few hundred years we will have summer in November" and Christmas in summer, said Younas Khan, a physics instructor at the University of Alabama at Birmingham. Some people treat Feb. 29 "as a free day" to do things "they've long been putting off," Phil Plait said at Scientific American. "I think that's a pretty good idea because, after all, catching up is what leap day is all about," astronomically speaking.

What next?
There will be leap days every four years until the next skip year, 2100 — or till the Gregorian calendar is changed.