160116

No matter what you choose, you will gain the same symbol. If you choose 32, 3+2=5 and 32-5=27. 27 may be the mushroom. If you choose 37, then you will have a number which is 5 more than 32. So the sum is 3+2+5. The ‘5’s cancel each other out so you still get 27. If you go 10 more than 32 aka 42, you will inevitably get 9 more than 27 aka 36. Every multiple of 9 has the same symbol and whatever you choose, you will get a multiple of 9. The computer finds the symbol of a multiple of 9, finding the symbol you chose.