Hal has a positive secret number. He performs a sequence of operations with
his secret number. He doubles the number, subtracts 8, divides by 4, adds 2 and
squares the result to get 25. What is Hal’s secret number?
Let's work backwards to find Hal's secret number.
1. We start with 25 and find its square root: √25 = 5.
2. We subtract 2: 5 - 2 = 3.
3. We divide by 4: 3 / 4 = 3/4.
4. We add 8: 3/4 + 8 = 8 3/4.
5. We double the number: 8 3/4 × 2 = 17 1/2.
Therefore, Hal's secret number is 17 1/2.