A Puzzle A Day: 2026-04-24

During a spectacular magic show, 'The Great Algebro' challenges an audience member to a mental math trick. He asks them to secretly choose any whole number greater than 0. Then, they are to perform a series of operations in their head: First, add 5 to their secret number. Second, multiply that result by 2. Third, subtract 4 from the new total. Fourth, divide the current number by 2. Finally, subtract their *original secret number* from this last result. The Great Algebro claims he can predict their final answer, every single time, no matter what number they started with. What number would The Great Algebro predict?
Correct: 3
Let's use basic algebra to follow the steps: 1. Let the secret whole number be 'x'. 2. Add 5: x + 5 3. Multiply the result by 2: 2 * (x + 5) = 2x + 10 4. Subtract 4 from this new total: (2x + 10) - 4 = 2x + 6 5. Divide the current number by 2: (2x + 6) / 2 = x + 3 6. Finally, subtract the original secret number: (x + 3) - x = 3 No matter what whole number 'x' (greater than 0) you start with, following these steps will always lead to the number 3. Thus, The Great Algebro would predict 3.
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