So the most famous annual rugby tournament in the world is underway. And for France, it has started in style as they blew away under the lights in Paris on Friday night to record a 43-0 win.

The pre-tournament favourites, inspired by the mercurial Antoine Dupont, ran in seven unanswered tries to pile more pressure on Welsh coach Warren Gatland.

The visitors failed to record a single score in a game for the first time since the Five Nations became Six in 2000, while Les Bleus laid down a marker by taking the maximum five points.

But how exactly does the bonus point system work in the Six Nations? Express Sport explains.....

Until 2017, the followed a rigid and traditional league format. Wins were worth two points, a draw one, and teams level in the table at the end of the tournament were separated by their on-field points difference from matches played.

But that year, organisers altered regulations to fall in line with other professional club and international tournaments in rugby union. Wins were deemed worthy of four points, and a draw became worth two to each side involved.

Most critically, though, a bonus point system was introduced. The change of rules was intended to encourage the six teams involved to play a more attacking brand of rugby.

The answer is simple. A team that scores four tries in a game will receive an additional point, irrespective of whether they win, loseor draw. On Friday, France had theirs wrapped up before half-time when Louis Bielle-Biarrey crossed to make it 26-0.

But you can still be soundly beaten and go away with a point for scoring four tries. The notion encourages sides who are well behind on the scoreboard to keep attacking until the final moments.

This is, again, simple. Any team that loses by seven points or less also gains a point. This essentially means that teams can still lose and go away with a maximum of two points - if they are within the necessary margin while also crossing the line four times.

As soon as the new rules were announced, mathematicians were already pointing to a scenario where a team could win a Grand Slam and yet finish second in the table. In theory, five wins could only be worth 20 if no bonus points were scored - while it is possible to notch four victories and get 21 or 22 overall.

Organisers have safeguarded against such farce, though, by automatically awarding three additional points for a side that completes a Grand Slam. Therefore, the minimum total would be 23, guaranteeing them the top spot in the table.