If you ask someone to choose ten random digits (not including 0) and multiply them all together, then to tell you all but one of the digits of the answer, you can predict the remaining digit.
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This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.
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What do you mean? If I choose ten '1's, their product is 1. So I will tell that person nothing (all but one). However there are many possible digits.
If there were a dislike button I would have pressed it.
Let the random digits be a1,a2,a3,…,a10 NOT respectively, where a10 is the digit not told to you.
The product will be P=a1a2a3…a10, and the digits told to you will be a1,a2,a3,…,a9.
The remaining digit is obtained by dividing P by a1,a2,a3,…,a9 one by one, which equals to a10.
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This is an extremely fun question, as well as easy. :)