The Math Trick Puzzle

The answer is 5.

Explanation:
Let the number you pick be $x$:

1. Multiply it by 2:
   $2x$
2. Add 10:
   $2x+10$
3. Divide it by 2:
   2x+102=x+5\frac{2x + 10}{2} = x + 522x+10​=x+5
4. Subtract the original number ($x$):
   $x+5-x=5$

The result is always 5, regardless of the number you start with.