Slam bidding. No-trump slam
With No Trumps you can't deal with weak suits by ruffing. It's all about sheer HCP strength and precision bidding, hence the name "quantitative bidding" that is used to describe one way of looking for a Slam in No Trumps.
Quantitative bidding
Experience and logic both say that you need
- 37 HCP for NT Grand Slam
- 33 HCP for NT Small Slam
With only 36 HCP, you might be short of an Ac ! So 37 is a sensible minimum for a Grand Slam in No Trumps.
If from the bidding so far you can see that 33 is
- certain: then bid 6NT immediately, assuming that partner's limit bid precludes 37+
- only possible: then bid 4NT, to invite your partner to go to 6NT if he has his maximum HCP
If from the bidding so far you can see that 37 is
- certain: bid 7NT
- only possible: bid 5NT, inviting to 7. (Note that in a suit contract such a bid is also sometimes treated as a Grand Slam Force).
What are the probabilities of success with these levels, and what probabilities should you require if using other techniques? Based on the prizes for success and failure, and the possibiliy of being doubled, it's
- 75% for a Grand Slam
- 50% for a small Slam
Asking for Aces in a NT contract
The bidding may have proceded in such a way that you really need to know about controls. For example, the bidding could have revealed slightly fewer than 33HCP overall, but a long winning suit, so that given controls in all the other suits, then a Slam could be on. So, ask for Aces.
Beware: 4NT is not asking for Aces when you are playing in No Trumps. First, it's a quantitative bid as described above. And secondly it's better to agree to use Gerber 4when asking for Aces and Kings in No Trump contracts.
4NT does mean Blackwood if a suit has been established.