Question

Fred told Wilma to pick a number and then do the following steps: Double the number, Add 6, Multiply by 5, Subtract 10, Divide by 4. Wilma says she got 10. What number did she start with?

Answer 1

Working backwards from Wilma's final answer of 10 through the operations she performed, we find that the original number she picked was 2.

Step-by-step explanation:

Step-by-Step Backwards Calculation

Let's work backwards through the operations Wilma performed:

1. First, reverse the division by 4, so multiply Wilma's final number by 4: 10 × 4 = 40.
2. Next, add 10 to this result since the last operation was to subtract 10: 40 + 10 = 50.
3. Now, divide by 5 to undo the multiplication by 5: 50 ÷ 5 = 10.
4. Subtract 6 to reverse the addition of 6: 10 - 6 = 4.
5. Finally, because the first operation was to double the number, divide by 2 to find the original number: 4 ÷ 2 = 2.

Therefore, the number Wilma originally picked was 2.