How to play
- Goal
- Fill every row and column with 1–N, once each, while satisfying the corner arithmetic and parity seals.
- How it ends
- A chart finishes when all cells are filled, every Latin row and column is correct, and every seal holds; Undo and Erase allow corrections.
- Record
- Your first unassisted finish keeps your time for that chart; later plays are practice.
- Fill each row and column with every digit from 1 to the grid’s size exactly once. Fixed given digits cannot be changed.
- A circle with a number and +, −, × or ÷ applies independently to each diagonally opposite pair around it. Both pairs must reach that same target.
- Subtraction means the absolute difference, including zero. Division means the larger digit divided by the smaller exactly; never round a quotient.
- E requires all four surrounding cells to be even. O requires all four to be odd. An absent seal adds no restriction; there are no Sudoku boxes or main-diagonal rules.
- Choose a digit or Erase and tap a cell, or paint a stroke. Inspect seal highlights a seal beside the focused cell and explains its rule.
- Release commits one stroke as one Undo. Escape, resize, pointer loss or a second finger cancels a stroke. Restart keeps the original clock; reload retains marks and Undo, and a resumed finish stays local.
Controls
| Mouse / touch | Choose a digit or Erase, then tap or paint cells; Inspect seal explains a corner near the cursor |
|---|---|
| Arrows + Enter / Space | Move the cursor and apply the selected digit |
| 1–N / 0 | Select and enter that digit / erase; repeating a digit keeps it |
| Delete / Backspace | Erase the focused editable cell |
| Z / Y | Undo / Redo |
| R / Restart | Confirm clearing entries while keeping the first clock running |
| Escape | Cancel a stroke, close a dialog or return to the atlas |
| Controller | D-pad moves; A enters; X changes digit; Y erases; shoulders Undo/Redo; B cancels/back; Start settings; Back rules |
Tips for Mathrax
- Read both diagonals Treat a seal as two separate equations with the same answer.
- Combine with missing digits A row or column’s unused digits narrow each corner equation.
- Use parity first E removes every odd candidate from four cells; O removes every even candidate.
- Keep corrections reversible Inspect seal explains its rule. Erase and Undo let you correct a digit without resetting the clock.
Questions about this game
Does Mathrax have Sudoku boxes?
No. Only rows, columns, fixed givens and the printed corner seals constrain a chart.
Does a seal add all four digits?
No. It applies separately to northwest/southeast and northeast/southwest pairs.
Which order do subtraction and division use?
For subtraction take the absolute difference. For division divide the larger by the smaller exactly.
What do E and O mean?
All four surrounding digits must be even or odd respectively.
Can I replace a given digit?
No. Its distinct green tile remains fixed.
Can replay improve my first time?
No. Your first saved finish remains unchanged; replay is practice.
All charts are open. Reload retains an unfinished first attempt, Undo and its original clock; resumed finishes stay local. Practice reopens fresh and preserves your first time.
Watch how to play
About Mathrax
Solve the brass arithmetician’s corner equations in an arcane laboratory. Each seal speaks to two diagonal pairs; no Sudoku boxes apply.
All 160 original charts are open: forty 4×4, sixty 5×5 and sixty 6×6. Every chart has one independently proved answer and a complete bounded deduction.
Your first finish keeps its time. An uninterrupted verified first solve can claim the named fastest time; replay is practice.
