A: First let’s just note that the normal way to win is to take two number Keepers and essentially “graft” them together. Let’s call this “passive grafting.” If a Math Victory Rule is in play, it lets you use math instead of “passive grafting” (aka “the normal way”). The Grafting Rule is meant to make it possible to create two-digit numbers for the specific purpose of subsequently using them in an equation to reach the Goal number via calculation.
For everything in Math Fluxx, you can only use numbers you can see. You can only Graft or “passively graft” numbers you can see, and you can only use numbers you can see in an equation. Having the Grafting Rule in play just lets you take two numbers-you-can-see and make them into a two-digit number-you-can-see to write out your equation.
For example, here is the equation to win Silver Jubilee (25) with Keepers One, Five, and Ten by grafting One and Five into Fifteen, and then adding it to Ten:
1 5 + 10 = 25
By contrast, here’s an illustration of how you CAN’T write out the equation to win When I’m Sixty-Four with a One, Three, and Six by taking (1+3=4) and then grafting the resulting “4” with the Six to make 64.
6 ? (3+1) =
There is no mathematical operator that functions like “grafting” so there’s nothing you could put in place of that question-mark.