THE IDEA: EVERY ROW IS A SUM
A Number Crossword is black cells and white cells, like any crossword. Each run — a straight line of white cells going across — is one whole number, and the black cell at the start of the run holds a little arithmetic clue (like 9 × 8 or 86 + 243). Work the clue out, and that's your answer for the row.
Two things, that's the whole game:
- Each across run equals its clue. Read the run left to right as a multi-digit number; it has to match the sum in the black cell.
- It's across only — no down clues. The columns don't have to mean anything. Every row stands alone, so you can solve them in any order you like.
That "no down clues" bit is the kindness: nothing cascades, nothing traps you. Each row is a fresh little sum with no strings attached.
LET'S ACTUALLY SOLVE ONE — STEP BY STEP
Here's a real Number Crossword. Black cells with little sums, white cells waiting for digits. Don't take in the whole thing — we only ever look at one row at a time.
The starting grid — a sum in each black cell, white cells empty.
Step 1 — pick a row and read its clue.
Take this row — its clue is 9 × 8. That's all the work the puzzle is asking for: what's 9 × 8? Straight off the times table — 72. Hold that number; we're about to drop it in.
Step 2 — count the cells, then write the digits in.
Quick sanity check before you write: the run is two cells, and 72 is a two-digit number. They match — good. Now just transcribe it left to right: 7, 2. One cell per digit, done. If your answer had the wrong number of digits for the row, that's your cue you've mis-added — recount, don't force it.
Step 3 — the digit-count check earns its keep on longer rows.
Look at the top row — 3 cells, clued 86 + 243. The cell count tells you what to expect before you add: 3 cells means the answer is a 3-digit number. Work it out — 86 + 243 = 329. Three digits for three cells. Perfect.
Step 4 — drop the digits in, same as before.
329 across the three cells: 3, 2, 9. No leading zeros to worry about here — a multi-digit answer never starts with 0, so if you ever compute something like "07" for a two-cell row, you've slipped a digit somewhere.
And that's the entire technique, repeated. No clever ordering, no waiting on another row — read the sum, work it out, count the cells, write it in. Do that for every row and the grid fills itself.
Done. Read any row across — it's exactly what its sum works out to. 👻
THE WHOLE METHOD, IN FOUR BEATS
Every row is the same little loop:
- Read the clue. It's in the black cell at the start of the run.
- Evaluate it to a single number. Normal maths order: × and ÷ before + and −.
- Count the cells. The answer's digit count must match the run length — a built-in error check.
- Write it in, left to right. One digit per cell. Move to the next row.
The only thing that ever goes wrong is arithmetic. If the digit count doesn't fit the row, you added wrong — recompute, don't squeeze.
A COUPLE OF FRIENDLY HABITS
- Evaluate fully before you place anything. Finish the sum in your head (or on the side), then transcribe. Computing and writing at the same time is where slips happen — especially on the harder tiers with chained clues like 5 × 12 + 7.
- Let the cell count guide you. Two cells? Expect a two-digit answer. Three cells? Three digits. It tells you what you're aiming for before you even start adding.
- Start with the row you find easiest. Across-only means order doesn't matter — knock out the times-table rows first for a quick win, then settle into the longer sums.
THAT'S IT — GO DO ONE
Read a sum, work it out, count the cells, write the digits in. It's the gentlest puzzle in GridJoy — no logic to untangle, no rule to trip over, just you and your times tables, with a ghost quietly cheering each row home. Brilliant for a warm-up, brilliant for kids learning their multiplications, and weirdly satisfying when a whole grid falls in under a minute.