Mike Bloomberg is supposed to be super-smart, but he somehow came up short on understanding the arithmetic of the Democratic Party primaries.

His belated entry into the 2020 race was supposed to provide a centrist alternative to Bernie Sanders. Instead, because of Democratic rules on delegate distribution, Bloomberg could put Sanders over the top on Super Tuesday, March 3.

Let’s stick to California, which I know best, although the Democratic requirement that a candidate must obtain 15 percent of the vote to get any presidential delegates applies to other states as well. (For those of you who follow The Cook Political Report, political analyst David Wasserman has been alerting readers to this dynamic.)

California will send 494 delegates to the July 13-16 Democratic National Convention in Milwaukee. Of this number, 271 will be chosen from the state’s 53 congressional districts.

Ninety delegates are awarded to the statewide “at-large” winner. There are another 54 pledged delegates statewide that will also go to the at-large winner plus 79 unpledged delegates that include Gov. Gavin Newsom, the members of Congress and other big shots.

The key factor is the 15 percent requirement.

The Public Policy Institute of California recently polled Democratic voters (and independents, or No Party Preference), who can select a Democratic ballot if they so choose. Sanders was way ahead with 32 percent. Four candidates — Bloomberg, Joe Biden, Pete Buttigieg and Elizabeth Warren — had between 14 percent and 12 percent.

If the statewide election actually comes out this way, Sanders would get all 90 at-large delegates plus the 54 pledged delegates. In this scenario, he’d probably clean up in many of the congressional districts as well.

That’s because the California rules discard the votes of any candidate who does not reach the 15 percent threshold. Say, for example, Bloomberg and Biden reach the threshold and Buttigieg and Warren do not. Then Buttigieg’s and Warren’s votes would be discarded, even though together they might have as much as 28 percent of the total vote. If lesser candidates are included, as much as 40 percent of the vote could be simply discarded.

Sanders, Bloomberg and Biden would then share the delegates, with the largest percentage going to the winner. This would give Sanders many more delegates than he would earn in a true proportional system without the threshold and the discarding of the votes of anyone who does not reach 15 percent.

It’s the latter quirk that balloons the delegates for the winner and anyone else who qualifies.

Bloomberg may have reasoned that the election would come down to a contest between him and Sanders, and that both of them would profit from the discarded votes. But that was always an unlikely scenario, given that Bloomberg is not on any ballot until March 3.

There would be no reason to expect other centrists to drop out before Super Tuesday after participating in only two caucuses and two primaries, counting the South Carolina primary this Saturday.

Given the arithmetic of the primaries, the Bloomberg equation was defective from the outset. That’s not to say that he or one of the other candidates couldn’t make chicken salad from this mess. But the rules — and much else — favor Sanders.

One other point: California has a notoriously slow vote count, and counting ballots in the congressional districts will take time. We’ll probably know the statewide winner on March 3 or March 4, but we won’t know how many delegates earned if any of the candidates are close to the 15 percent threshold. State officials are trying to lower expectations and say the delegate allocations won’t be known until the vote is certified on April 2.

Lou Cannon, a Summerland resident, is a longtime national political writer and acclaimed presidential biographer. His most recent book — co-authored with his son, Carl — is Reagan’s Disciple: George W. Bush’s Troubled Quest for a Presidential Legacy. Cannon also is an editorial adviser to State Net Capitol Journal, which published this column originally. Click here to read previous columns. The opinions expressed are his own.

Lou Cannon, a Summerland resident, is a longtime national political writer and acclaimed presidential biographer. His most recent book — co-authored with his son, Carl — is Reagan’s Disciple: George W. Bush’s Troubled Quest for a Presidential Legacy. Cannon also is an editorial adviser to State Net Capitol Journal, which published this column originally. Click here to read previous columns. The opinions expressed are his own.