
Missing Digits: Math Puzzle
Crack the hidden numbers
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Free
About
Uncover the hidden digits by reasoning, not guessing.
4■2 + ■8■ = 12■5.
Guessing gets you nowhere. But follow the carry from the ones column,
and the answer narrows to exactly one possibility.
FUKUMEN does one thing: missing-digit arithmetic, done beautifully, forever.
■ Features
- Endless puzzles, generated on your device
From simple addition to full long multiplication with three partial-product rows.
You will not see the same puzzle twice.
- Exactly one answer, always
Each puzzle starts as a completed sum, then digits are hidden — but only up to
the point where a second answer would become possible. Every puzzle is verified
before it reaches you. No unsolvable boards. No ambiguous boards.
- Four difficulties
Easy and Normal are addition. Hard and Oni are long multiplication.
At Oni, 19 of the 26 cells are blank.
- Today's puzzle
One puzzle a day, the same one for everyone. Streaks and a calendar
keep your history visible.
- A real long-form layout
Chalk on a blackboard, set vertically the way you'd write it by hand.
Tap a blank, type a digit. The board scales up when the numbers are short.
- Quiet help
Columns that can't work out are tinted, gently — you can turn this off.
And if you're truly stuck, a hint opens a single cell.
- Records
Puzzles solved, streak, average time, best time per difficulty.
■ Who it's for
- Sudoku and crossword solvers looking for something that actually uses arithmetic
- Anyone who wants to deduce rather than drill
- Parents and kids working through missing-digit problems for entrance exams
- People building a small daily thinking habit
- Anyone who needs a puzzle that works with no signal — trains, planes, anywhere
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What's New in Missing Digits
1.0
August 21, 2026



