Here's what helped me out. First off, like the game says, DO NOT be afraid to PASS. You only lose 3 points per pass in hopes of a potential 50+. Also, some simply aren't solvable and award you with 20 bonus points for passing. In most cases, if all numbers are below 5 then just skip it. Even if it's solvable, if you aren't getting ATLEAST 30 or more points it's not worth it. I don't know how many points you need for the "special item", however after I tried the above method I got it first try for 250 points. :p
That is the solver for Rydia's Math Magic game in FFIV. Another game by Maxtrix, lol. That game also required you to make 10s. Just type the 4 numbers in without spaces and hit submit and it'll give you all the possible ways of making 10.
The points are based off the answer to any operation you do. So 9x9 will give you the max gain of 81 points. So try to use multiply as much as you can. The solver above is obviously if you just want the beastmaster quickly, don't use it if you want the math challenge. :P
After each successful pass (where the numbers were unsolvable) the penalty for passing increases by 1. Still very important to pass if you are not getting over 80 points per round.
There are 2 heuristic algorithms that i do in my head when I play the minigame:
1. Look for 2 of the same number. If the other 2 number sum to 10, add those numbers. Then multiply and divide by the duplicate digits.
2. For maximum points try to plug the numbers into this equation: (((A * B) + C) / D). You get a lot of points for the initial multiplication then slightly more for the addition, then ten for the division. Can also use subtraction in the place of addition for slightly lower points.
My record is for the minigame is around 320 points.