Zoggle publishes three questions a day and never takes them down. If you found the game late, or missed a week, nothing is lost — start anywhere in the list above and work backwards.
Playing an old puzzle does not affect your streak, so there is no penalty for catching up out of order and no way to game the streak by binge-playing the archive. Each day's three questions are scored on their own, and your result is stored in your browser alongside the rest.
One puzzle a day is a slow way to get better at anything. The archive is the faster route: play five or six in a row and the method starts to show itself, because you begin recognising the shape of a question before you have worked out the answer.
Most questions reduce to the same handful of moves. Population times a rate per person. Volume divided by volume. A daily figure multiplied out to a year. Once those become reflexes, the hard part stops being the arithmetic and starts being the choice of what to multiply — which is the actual skill.
If you want the method laid out properly rather than absorbed by repetition, the guides cover it directly: how to decompose a question, the anchor numbers worth knowing by heart, and the traps that make confident estimates wrong.