They would have to THROW the ball. A quick pass would not be fast enough.

If you want to challenge your brain, do multiplication and division in your head. Start with a problem on paper so you can do long division or multiple column of multiplication so you have to carry numbers in your head. Don't choose complex problems. This is exercise, not torture.

If the challenges are too tough and you cannot get the correct answer, try an easier challenge. You should be succeeding. This helps the brain improve. The brain learns by repeated successes, not failures.

Maybe adding columns of numbers would be a good start. Start with 10 rows of 2 digit numbers and add row by row, not column by column. Then, try 3 digit numbers.

There are some math games that give you a brief view of a number and an operand then another number. If you can do those successfully, fine. Do not do problems that you cannot succeed at.

Success causes chemicals in the brain that reinforce the skill. Failure does not cause these chemicals. It causes stress chemicals. You already have enough of those flooding your brain.

Do Minesweeper. It is about number pattern recognition.