Before you begin
Pick a number now, out loud
Do it before the first question. A guess made afterwards is not a guess — it is an adjustment, and it will quietly move towards whatever the questions suggest.
Why the gap is the point
The estimate at the end is worth something on its own. The distance between it and your first number is worth more, because that distance is exactly the amount of spending you currently have no view of.
People who guess close tend to have few subscriptions and one billing route. People who guess low tend to have several routes — a store, a card, PayPal — and no single screen that shows all three.
See the worked figureYour answers carry over