The missing weight in Number Balance is the single digit from 1 through 9 that makes both pans of a scale carry the same total, and the disclosed clean route through all five rounds is 4, 3, 4, 4, 8. Each round shows a fixed equation with known number blocks on the left pan and a mix of known blocks plus a question-mark block on the right. Your only task is to read both pans, sum them mentally, and press the one digit that closes the gap. Number Balance is built around elementary addition rather than estimation, pattern recognition, or speed, so the right answer follows directly from the visible blocks. Because every round is independent, a wrong choice never changes the equation ahead; it only counts against you. That design lets you recalculate after a first mistake but ends the run if you slip a second time. Restart always returns you to the same first scale, with zero points and zero mistakes, so the run is fully repeatable from any state.
What Each Round Actually Shows You
Number Balance runs through five disclosed rounds, and every round uses the same visual layout. A scale graphic sits in the center of the page, with a left pan, a right pan, and a horizontal beam that should sit level when both totals match. The left pan carries one or more printed number blocks; the right pan carries a smaller set of printed number blocks plus one block whose face is a question mark. The question-mark block is the unknown weight, and it is the only value you control. There is never an unknown block on the left, which keeps every round to a single subtraction.
The five equations are not generated, randomized, or rotated between visits. They are the same five fixtures every time you open Number Balance. Round one shows 2 and 3 on the left against 1 and the question mark on the right. Round two shows 7 on the left against 2, 2, and the question mark. Round three shows 1, 4, and 2 on the left against 3 and the question mark. Round four shows 9 and 1 on the left against 6 and the question mark. Round five shows 3, 3, and 3 on the left against 1 and the question mark. Knowing this layout in advance tells you exactly what kind of decision you are making on every round: the left total is a sum of visible single-digit numbers, the right total is a sum of visible single-digit numbers plus one unknown digit, and equality requires that the unknown equal the difference between the two visible sums.
Pick the Missing Weight Step by Step
- Read the left pan first and add the visible number blocks to get the left total.
- Read the right pan and add every block that carries a printed number; ignore the question-mark block for this step.
- Subtract the right visible total from the left total. The result is the only value the missing weight can take on this scale.
- Press the matching digit key from 1 through 9, or click the matching button on a touch device.
- Confirm that the pan is level, the score advances by 200, and the next scale loads automatically. If the same scale remains visible, your digit was wrong and the mistake counter has incremented.
Worked example for round one: the left pan shows 2 and 3, so the left total is 5. The right pan shows 1 and the question mark, so the right visible total is 1. The difference is 5 − 1 = 4, which is the digit you press. Both pans now total 5 and the scale accepts the answer. Worked example for round two: the left pan shows 7, so the left total is 7. The right pan shows 2, 2, and the question mark, so the right visible total is 4. The difference is 7 − 4 = 3, and pressing 3 makes both pans total 7. The same one-step subtraction produces 4 for round three, 4 for round four, and 8 for round five, which is why the disclosed clean keyboard route through all five rounds is 4, 3, 4, 4, 8.
You can also reason from the right side instead of subtracting. If the right visible total plus the candidate digit equals the left total, the candidate is correct; if it overshoots or undershoots, it is wrong. That second framing is useful when the difference lands on a digit you might have misread, because the addition check forces you to verify both pans rather than trust a single subtraction.
Putting the Five Rounds Together
| Round | Left pan blocks | Right pan known blocks | Left total | Right visible total | Missing weight |
|---|---|---|---|---|---|
| 1 | 2, 3 | 1 | 5 | 1 | 4 |
| 2 | 7 | 2, 2 | 7 | 4 | 3 |
| 3 | 1, 4, 2 | 3 | 7 | 3 | 4 |
| 4 | 9, 1 | 6 | 10 | 6 | 4 |
| 5 | 3, 3, 3 | 1 | 9 | 1 | 8 |
Reading the table from left to right shows the exact subtraction behind each press. Round four is the only scale where the left total reaches two digits, because 9 + 1 = 10, but the missing weight is still a single digit because the right pan already sums to 6. The same logic produces 4 for round four (10 − 6 = 4) and 8 for round five (9 − 1 = 8). The repeated 4 across rounds one, three, and four is not a pattern you need to memorize; it falls out of three different subtractions that happen to land on the same digit. Each scale is independent, so a clean run through the disclosed fixtures types 4, 3, 4, 4, 8 in order.
Score, Mistakes, and the Two-Strike Rule
Each correct answer adds 200 points and advances the game to the next scale. Five correct answers produce a maximum score of 1,000 points, which is the same total you see after a clean keyboard run of 4, 3, 4, 4, 8. The game has no speed bonus, combo multiplier, or hidden timer, so the score depends only on how many scales you balance correctly. The score and mistake counter reset only when you press Restart.
A wrong answer behaves differently from a correct one. The current scale stays on screen, the mistake counter becomes 1, and you still have a chance to recalculate both pans and try again. This is the one recoverable state in the game. A second wrong answer on any scale increments the mistake counter to 2, which creates a terminal deadlock. Once the run is deadlocked, further digit presses are ignored until you press Restart, so the second mistake is the point of no return.
Restart returns the game to the first scale (2 and 3 on the left, 1 and the question mark on the right) with zero points and zero mistakes. The best score is stored only in the current browser's localStorage, so it persists across sessions on the same browser but is not shared across devices. The five equations themselves never change between sessions, so each Restart is a fresh attempt at the same disclosed route.
Why the Answer Is Always a Single Digit
Every disclosed fixture in Number Balance has exactly one valid single-digit solution in the 1-through-9 button range. The game deliberately excludes 0 and any two-digit answer, which keeps the decision set small and the keypad legible. For a closer look at why zero and values above 9 never appear, the Number Balance guide on missing weight limits walks through each of the five equations and shows that every neighboring digit in the 1-through-9 range fails to balance its scale.
This constraint is what lets the game treat a single key press as a complete answer. There is no need to confirm, no second-stage input, and no way to enter a value outside the visible button row. If you press the wrong digit, the scale stays put and you get one chance to retry before the run locks. If you press a key outside 1 through 9, the state stays unchanged and no mistake is counted.
Keyboard, Mouse, Restart, and the Boss Key
Every action in Number Balance has both a keyboard path and a pointing-device path. Pressing any digit key from 1 through 9 submits that digit as the missing weight and checks it against the current scale. Mouse and touch users can press the same nine buttons that sit below the scale. Invalid keys, including 0 and any key above 9, leave the state unchanged, so a stray keypress cannot break your run.
Restart is available at any time, including after a perfect run, and it always returns you to the same first scale with a clean scoreboard. Double-pressing Escape toggles a simulated spreadsheet boss screen over the game; pressing Escape twice again resumes the same scale in the same state. The boss screen is purely visual and does not change the score, the mistake counter, or the scale layout underneath.
Number Balance is fully keyboard-accessible and works on narrow screens because the scale is rendered with semantic HTML and CSS rather than canvas. There is no audio, no download, no account, no network call, and no pointer precision requirement, so the only input you have to master is reading both pans and picking the right digit. The same five disclosed fixtures appear every time you load the page, which is what makes the next-step decision a logic test rather than a guessing game.
For a deeper look, see How to Choose Your Next Step in the 1 to 9 Number Game.