Alien abduction
You have been abducted by aliens and they agree not to eat you as long as you can solve their puzzle.
They give you 9 identical balls, one that is heavier than all the others, and a pan balance. What is the minimum number of times you have to use the pan balance (you can't use your hands or any other objects) to figure out the heaviest ball?
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1 solution
Step 1: Spilt the balls into 3 portions and weigh two of the portions.
Step 2: If the right side of the pan balance is heavier than the left, then get rid of the other six balls, same for the left side. If the pan balance is balanced, then take the balls that you didn't put on the balance and take them to step 3.
Step 3: Take the 3 balls and weigh two of them, then do the same thing mentioned in step 2.
Step 4: Celebrate your win against the aliens!