Blackwood

A method of ensuring a sufficient quantity of aces are held by a side before committing the auction to a small or grand slam. 4NT asks partner for the quantity of aces held - the responses are:

5 - 0 or all 4 aces

5 - 1 ace

5 - 2 aces

5 - 3 aces

Some pairs added void showing responses which are:

5NT - 2 aces and a void

6 - 1 ace and a void in the bid suit

unless that suit was trumps in

which case the void was in a higher

ranking suit

If the 4NT bidder discovered that ALL aces were held by their side AND WAS INTERESTED IN A GRAND SLAM, he could bid 5NT asking for Kings. The responses are the same as for aces (i.e 6 for 0 or 4 Kings etc).