This slam demands usually 3 out of 3 small important cards (♥10, ♠J, ♣J) in partner's hand to be a good one. Some numbers: - Partner will have ♠J in 4/10 cases (40%) or we need the suit to be 3-3, for a total of 60% chance -Partner will have ♥10 in 3/9 cases (33%) or we need the suit to break 3-3 for a total of 55% chance -Partner will have ♣J in 3/8 cases (37,5%) or we need the suit to break 3-2 for a total of 80% chances It depends a lot of your opening style. -If you open usually with 11+ hcp, the slam will be a 55% affair -If you open usually with 10+ hcp with this shape it will be something like ((55% x 80%) +(55% x60%))/2 =38.5%