Choosing your next step in the four-bit binary game means reading the four binary digits from left to right as place values 8, 4, 2, and 1, summing the digits that are 1, and entering that decimal on the keyboard before pressing Enter. That single decision repeats five times across the run: look at the four-bit code on the screen, decide which bits are set, type the resulting decimal, and submit. There is no menu of moves, no branching path, and no hidden difficulty curve, so "choosing the next step" collapses to one precise conversion per round. What makes that next step feel like a decision is timing and risk. The fixed order of the five rounds is 0001, 0011, 0110, 1010, and 1111, so once you finish round one you already know what the next code will be. The real choices are how confidently you read it, whether you recheck the bits before pressing Enter, and what you do when the entry clears after a mistake. Treat every submit as a discrete decision, not a reflex, and the run becomes a sequence of five deliberate moves rather than five coin flips.
The five fixed codes and their decimal answers
The four-bit binary game uses the same five codes every run, so you can plan the entire route before you start. Each code, read left to right, corresponds to a single decimal answer between 1 and 15, and submitting all five correctly finishes the run at exactly 1,000 points. Because the codes never shuffle, the next step on screen after a correct submit is always a known quantity rather than a surprise.
| Round | Code shown | Set place values | Decimal to enter | Points after submit |
|---|---|---|---|---|
| 1 | 0001 | 1 | 1 | 200 |
| 2 | 0011 | 2, 1 | 3 | 400 |
| 3 | 0110 | 4, 2 | 6 | 600 |
| 4 | 1010 | 8, 2 | 10 | 800 |
| 5 | 1111 | 8, 4, 2, 1 | 15 | 1,000 |
If you memorise the five-decimal key 1, 3, 6, 10, 15, every next step becomes a matter of typing a known answer for the next fixed code. Per the randomness analysis for the four-bit binary game, that reproducibility is by design and is what lets the score cap at exactly 1,000 points across every clean run.
How to read place values so your next answer is correct
Every correct next step starts the same way: identify the four place values from left to right, mark which bits are set to 1, and add them. The place values are always 8, 4, 2, and 1 in that fixed order, so once you know the leftmost bit is set you already know the answer is at least 8. The Binary Decoder Game renders each code in large monospaced text so the four columns line up clearly, which makes the place-value reading especially easy compared to handwritten conversions.
- Read the four binary digits from left to right as place values 8, 4, 2, and 1 in that fixed order.
- Note which positions show a 1; only those places contribute to the total.
- Add the set place values together to get the decimal answer, for example 8 plus 2 for 1010.
- Type the decimal result on the keyboard, use Backspace to fix any typo, and confirm the entry has at most two digits because every answer fits in the 0-to-15 range.
- Press Enter to submit, watch the code advance to the next fixed round, and prepare for the same five-step conversion again.
This sequence works because binary is a positional system with radix two, so reading left to right and doubling the running value as you go produces the same decimal whether you add the place values or accumulate bit by bit. NIST IR 8354 documents binary digits and four-bit groupings as the standard reference for that positional reading, and MDN's parseInt documentation confirms that only the characters 0 and 1 are valid inside a binary numeral. The pure decoder enforces the same rule locally in your browser, so what you see as four columns on screen matches exactly what the validator checks.
Recover from your first mistake and avoid the second
The next step after a wrong answer is not the same as the next step after a correct one. A correct submission advances the round and adds 200 points, so the next code on screen is the next fixed entry in the sequence. A wrong submission does not advance. It clears your typed decimal, leaves the same code visible, and counts as mistake one of two. The run only ends when a second wrong submission arrives for the same code, at which point the interface enters a terminal deadlock and the Restart control is the only way forward.
That asymmetry is what makes your next decision after a slip so important. The same code is still on screen, you still have one full attempt left, and a correct second try both recovers the round and earns the 200 points as if nothing went wrong. The mistake is not the submission; the mistake is treating the cleared entry as a fresh guess instead of as a chance to recheck the bits. Pause, recount the place values 8, 4, 2, 1, retype the decimal, and submit again. As long as you avoid a second wrong submission on the same code, your run continues with a fully recoverable mistake record and the same five-round sequence still on the table.
A worked example: choosing the answer for 1010
By round four the code is 1010, which is the most common place where readers hesitate because the digits alternate. Reading it left to right with place values 8, 4, 2, and 1 gives 1 in the 8 place, 0 in the 4 place, 1 in the 2 place, and 0 in the 1 place. The set places are 8 and 2, and 8 plus 2 equals 10, so the decimal answer to type is 10 and the Enter key submits it for 200 points. After a correct submit the next code becomes 1111, whose set places are 8, 4, 2, and 1, summing to 15 for the fifth and final 200-point entry that brings the total to exactly 1,000.
If you type 2 by mistake and press Enter, the entry clears and the code stays 1010. The next step is to count again: bit one is set, bit three is set, so the total is still 10. Type 1, then 0, then Enter, and the run continues without losing points or rounds. That single recovery is the entire difference between a perfect 1,000-point run and a locked screen, and it is the reason round four rewards a careful recount over a fast guess.
Score, restart, and the boss-key controls
Knowing what to choose next is only half the game; knowing what the surrounding controls do keeps your run safe if you slip. Each correct answer awards 200 points and advances the round, so a five-round clean run lands exactly on 1,000 points. A wrong answer clears the typed decimal but leaves the same code on screen, with the run ending only after a second wrong submission. Restart returns the game to 0001 with zero points and zero mistakes, which is the fastest way to reset a locked run. Double-press Escape for the shared simulated spreadsheet boss screen, and repeat the gesture to resume the current code unchanged. A completed best score is stored only in localStorage on your own device, with no network request, no account, and no server computation involved at any point. Every check, including the 200-point award and the deadlock detection, runs locally in your browser.
Adjacent number puzzles to try next
Once you have the five-decimal key 1, 3, 6, 10, 15 memorised, four adjacent number puzzles make good follow-ups. Number Sequence Quiz asks you to identify five arithmetic patterns before two mistakes end the run, which trains the same read-decide-submit loop on a different rule. Number Fill-In puts 1, 2, and 3 into every row and column of a small grid, which is a useful change of pace for spatial reasoning. Magic Square forces every row, column, and diagonal to the same magic constant, and Math Maze lets you apply the four basic operations to reach exactly 10. Together with Binary Decoder Game, they form a tight set of short, deterministic browser puzzles where each next step is a clear decision rather than a gamble.