By Barbara Seagram 
Courtesy of BarbaraSeagram.com
North knows that South has promised 22-23 HCP by his rebid of 2NT. Simple arithmetic: 22 + 12 HCP = 34 HCP. North knows that his side cannot be missing two aces as that would add to 8 HCP, so he bids 6NT with gay abandon.
Declarer counts tricks. West leads the ♠10. East wins the ♠A and leads back a spade. South wins it with the king. Count your winners!
♠ 2 ♥ 3 ♦ 3 ♣ 3
That’s only eleven winners and you need twelve to make 6NT. If hearts break 3-3, all will be well. Similarly, if diamonds break 3-3, you are all set. But the odds are not with you. When you are missing six cards in a suit, they rate to divide 4-2. Diamonds offer you the best possibility for an extra trick because your side also owns the ♦10. You must postpone playing the diamond suit for now because you first need to discover more information about the other suits and how they are behaving. Cash the third spade now — East fails to follow. Deduction: West started with five spades.
Cash three rounds of hearts — West fails to follow on third round. Deduction: West started with two hearts. Cash three rounds of clubs — West fails to follow on third round. Deduction: West started with two clubs. Ergo… drumroll please! West started with four diamonds, and East has only two diamonds. East could have the doubleton ♦J, so you first cash ♦A and ♦K and now finesse West for the ♦J, knowing with confidence that East cannot have another diamond.