The most important number in National Party leader Judith Collins' reshuffle is 17.
That is the number of MPs that it would take for any challenger to get a leadership change in the National Party.
It means that is the minimum number of MPs she has to keep happy.
That number might explain why Collins has gone to such great lengths to reward one of her apostles, Andrew Bayly, in her otherwise reasonable reshuffle.
Collins had intended to put Simon Bridges in the Finance role.
Bridges was not the only contender. A number of MPs asked for it and Michael Woodhouse or Todd McClay were other options.
But Bridges was the best for what National needs now: someone with some grounding in the portfolio, a good front bench performer who knows what hard work actually means, and who can identify issues ripe for political attacks.
It is a particularly critical portfolio this term, as the Government wrestles with the impact of its actions to keep Covid-19 out.
After Tuesday's caucus meeting, Collins found a precedent for her continued leadership in former PM Jim Bolger's bad election result of 1987 before his "landslide victory" in 1990.
Of course, the Labour Government is unlikely to hand her anything as helpful in achieving that as the splits and divisions caused by Rogernomics were for Bolger then.
But Covid could lend a helping hand – Collins pointed to the predictions that the worst economic fallout would be 1.5 to 2 years down the track.
Given that, the best person for the job should have been Collins' only consideration.
She initially went for that best person in Bridges.
However, Bridges rejected it on the basis of her plan to split the portfolio into two.
That was a Finance and Treasurer role, with each taking responsibility for different aspects from tax to the Budget, which goes to Bayly.
Bridges did not believe it would work in practice, it was a recipe for mixed messages, watered down the Finance role too much, and it would make National look like fools.
Left with a choice of abandoning her plan and keeping Bridges, or finding another Finance spokesman to work with Bayly, she went for the latter.
Bridges can hardly be blamed for rejecting the proposed role, although he no doubt knew it risked being portrayed as a bit of a tantrum.
Collins' reasoning for the split was that Bayly's background in accountancy qualified him to handle the detailed nuts and bolts of the portfolio.
She believed Bayly was qualified to win back the boardrooms, while his counterpart – (Collins settled on Michael Woodhouse) – would do most of the work against Robertson in Parliament and the media.
In short, Bayly had the brains, but not the political brawn.
There seems no real logical reason for the split.
It might be a valid move if there was a Treasurer for that person to shadow, but there is not.
In Australia there are separate posts of Treasurer and Finance Minister, but New Zealand has long had just a Finance Minister who manages to do it all quite well.
That is currently Grant Robertson, who is no slouch in the portfolio despite his own lack of the accountancy qualifications Collins seems to deem so critical.
It is unlikely Robertson will show much respect for Collins' decision for Bayly to reserve himself for the backroom work, especially since he is ranked higher than Woodhouse.
Collins did not want Finance to be simply a political prize.
Yet she has treated it as one.
Collins clearly was not willing to sacrifice Bayly over Bridges, but equally did not consider Bayly himself was good enough to hold the full Finance portfolio himself.
Collins could easily have achieved the same end by giving Bayly portfolios such as Infrastructure and Revenue, and as an associate finance spokesman.
As a result, it looks very much as if the main reason Collins went ahead with her original plan was patronage: Bayly was one of her loyal supporters, and was being rewarded for that and kept sweet for when the next Race to 17 starts.
It was one inexplicable element in a reshuffle in which most other moves can be justified.
They include the decision to demote Todd Muller, and to also demote Paul Goldsmith but not by so much that he could claim to be harshly treated.
Christopher Luxon was wisely treated exactly the same as the other new MPs – unranked with smallish but decent portfolio (Local Government, in his case).
Those MPs who are not happy simply wait and watch. Fortunes change as leaders change, as Bayly has discovered.
It cost Bridges the third ranking in the caucus and he lost his second choice of Foreign Affairs as well.
Instead, Bridges was given seventh ranking, as well as Justice, Maori-Crown Relations, and Water.
So it was Water for Bridges – but Collins may well discover her reshuffle falls well short of a bridge over troubled waters.