What the challenge tests
Different starting numbers can merge into the same Kaprekar path, but they do not all arrive in the same number of steps. Today’s target asks you to reason backwards: choose digits whose first subtraction enters a path of exactly the required length. Rearrangements of the same four digits produce the same first difference, so changing digit order alone will not change the journey.
The target is generated deterministically from the UTC date and always falls between one and seven. Guesses are calculated locally in your browser. Your completion flag is stored only in local browser storage; no account or leaderboard is involved.
Strategy hints
Start from the end. Only a few numbers reach 6174 in one step, and they share a pattern: their largest and smallest digits differ by 6 and their middle digits by 2, because the first difference equals 999 × (largest − smallest digit) + 90 × (difference of the middle digits). For long targets, try inputs with one large digit and several equal small ones, such as 2111 (five steps) or 0014 (seven steps). Short targets usually need digits that are already spread out.
Seven steps is the maximum for any four-digit input, and three steps is the most common count. If you get stuck, the complete table on the numbers page lets you filter every input by its iteration count, and the article on why every number reaches 6174 explains the arithmetic behind the paths.