postulate!... this is a "play on word" mathematical riddle... a postulate is really a geometric term, but it is being used as "post you late."
There are different sizes of netballs so kids can play with smaller netballs and adults play with bigger ones. There is not a specific answer
Maths is very important in certain sports, as the calulations can assist in winning. In football its the geometric math predictions that can be drilled to then allow the players to understand how play might enable a win. This is true in most sports.
There is no specific IQ threshold for playing chess without a board and pieces, as chess relies more on strategic thinking, pattern recognition, and experience than on a quantifiable measure like IQ. Many skilled players can visualize moves and positions in their minds, which typically comes from practice and familiarity with the game. While a higher IQ might contribute to better problem-solving skills, effective chess play depends largely on training and mental discipline rather than a specific intelligence level.
The best way to play is to play to win.