THE IDEA: MAKE EVERY LINE HIT ITS TARGET
Every row has a target number on its right; every column has one along the bottom. Some squares are filled in already (those are your clues); the blank ones are yours to fill. Write a digit from 1 to 9 in each blank so that the numbers in each row add up to that row's target — and the numbers in each column add up to that column's target. Get every row and column right at the same time and it's solved.
That's the whole game. Two things to hold:
- Each line must total its target. No more, no less.
- Rows and columns share squares. A digit you write for a row also counts toward its column — so the two keep each other honest.
And the move that cracks it open needs almost no thinking — just a line with a single empty square.
LET'S ACTUALLY SOLVE ONE — STEP BY STEP
Here's a real Number Blocks. Some squares filled, some blank (those little dots), a target beside every row and under every column. Don't try to see the whole thing at once — we only ever look at one line.
The starting grid — dots mark the squares you still have to fill.
Step 1 — find a row with just one empty square.
Look at the second row: 1, 7, 6, ?, 7, and it has to total 26. The four digits already there add up to 21. So the one empty square must be 26 − 21 = 5. No guessing — with a single gap, the answer is forced. Write it in.
Step 2 — the exact same trick works down a column.
Now run your eye down the left column: ?, 1, 1, 6, 3, target 14. The filled digits make 11, so the top square is 14 − 11 = 3. Rows, columns — doesn't matter. Any line with one gap hands you a digit for free.
And here's why it's so moreish: every digit you write fills a square that another line was waiting on. Fill one gap and you very often hand the crossing row or column its own single gap. The board starts to tumble.
Cascading — a couple of fills later the middle row has one gap left and needs just a 7 to reach 25. Each square forces the next.
Done. Add up any row or column — it lands on the target every time. 👻
THE ONE MOVE, ON REPEAT
Number Blocks is basically a single trick you run again and again:
- Scan for a line with one empty square. A row or a column — whichever you spot first.
- Subtract. Add up the digits already in that line, and take the total from the target. That's the missing digit.
- Write it in, then look again. The square you just filled usually leaves a crossing line with one gap. Chase the chain.
Stuck with no single-gap line? Then a line with two gaps is hiding one: look for a square that can only be 1–9 in a single way once you respect both its row and its column. But on an easy grid you'll rarely need it — the one-gap chain carries you home.
THAT'S IT — GO DO ONE
Find a line with one gap, subtract to get the digit, write it in, and let the rows and columns trade hints until the grid fills itself. The first time one square cascades through half the board, you'll get why this one's such a comfy little brain-warmer — no words, no maths homework, no ads in the middle of your puzzle, just you, a grid of numbers, and a ghost who's quietly chuffed when the last square lands.