Best First-Guess Strategy for Deduction Puzzles

A strong opening guess buys you the most information for free. Here is how to choose one — and what to do with what it tells you.

Overview

In a deduction puzzle your first guess cannot realistically win, so its job is to reveal as much as possible. The best openers test a spread of distinct digits across all positions, because every "present" or "correct" result then carries unambiguous information about a specific digit.

A classic strong opener for a 4-digit, 0–9 code is four different digits such as 0-1-2-3, then a second probe with a fresh set such as 4-5-6-7. Together those two guesses test eight of the ten digits, so after just two moves you usually know most of which digits are in play.

Strategy & tips

• Open with four distinct digits, not repeats — repeats waste a slot that could have tested another digit.
• Follow up with a second guess using four new digits so your first two guesses cover eight of the ten possible digits.
• Once you know which digits are in the code, switch from discovery to placement: reuse those digits and shuffle their positions.
• Keep the very last guesses for confirmed candidates only — by then you should be placing, not exploring.

Worked example

A step-by-step solve showing how the color feedback narrows things down. (Digits shown here to teach the method — the live daily puzzle never reveals them.)

1. 0

   1

   2

   3

   Step 1. Opener 1: digits 1 and 3 are in the code (misplaced); 0 and 2 are out.

2. 4

   5

   6

   7

   Step 2. Opener 2: digit 6 is in the code (misplaced); 4, 5, 7 are out. After two guesses we already know 1, 3, 6 are in and most digits are ruled out.

3. 8

   3

   1

   6

   Step 3. The remaining unknown slot must be a digit not yet tested (8 or 9); placing 8 with the known 3, 1, 6 in their deduced spots gives 8316 — solved.

FAQ

Is there one mathematically optimal first guess?

Solver theory favors openers that maximize information, and any four-distinct-digit guess is close to optimal in practice. The exact "best" matters less than following up consistently.

Should I reuse my opening digits?

Yes — once an opener shows a digit is in the code, keep using it and focus on finding its correct position rather than re-testing whether it belongs.

Does the opener change day to day?

No. Because the puzzle structure is the same each day, a good general opener works every day; only the hidden code changes.

What if my opener gets all "absent"?

That is actually great information — it removes four digits at once and tells you the code is built from the remaining six.

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