Theo thinks of a number, then adds 11, doubles the result and finally subtracts 4.
What would the starting number be if the finishing number was 22?
You can use a flowchart to solve the problem:
If we start with the number, we do the steps as given above.
If we start with the answer, we move from right to left and do the opposite (inverse).
Answer is 22: do the opposite.
22 + 4 = 26
26 ÷ 2 = 13
13 – 11 = 2
The number Theo is thinking of is 2.
If we start with the number, we do the steps as given above.
If we start with the answer, we move from right to left and do the opposite (inverse).
Answer is 22: do the opposite.
22 + 4 = 26
26 ÷ 2 = 13
13 – 11 = 2
The number Theo is thinking of is 2.