Number Search Generator

What this generator does

Draws the list of numbers for you, hides them in a grid of digits in the directions you allow, and fills the rest with digits. It then re-scans the finished grid and, if any number can be read somewhere the answer key does not list, throws that grid away and builds another rather than printing a key that would mark a correct answer wrong.

How to use this tool

1. Choose where the numbers come from — a times table, counting in steps, or random numbers.
2. Set how many numbers to hide and how big the grid should be.
3. Choose the directions. Backwards numbers are offered only with four-digit numbers, for a reason the page explains.
4. Generate, print or copy the grid, and hand it out.
5. Show the answer key when you want to mark it.

Understanding the controls

Numbers

A times table, counting up in steps, or random numbers of three or four digits. A table starts at its first multiple of a hundred or more, because two-digit numbers cannot be hidden honestly.

Directions

Across and down, plus diagonals, plus backwards. Backwards is offered only with four-digit numbers: with every direction allowed there are around a thousand places a short number could be read by chance in a twelve-square grid.

How many numbers and grid size

Six to twenty numbers in a grid of eight to twenty squares a side. A crowded grid leaves little filler and makes the puzzle easy.

Seed (optional)

Any word rebuilds the same sheet, which is how you print a second copy of the one you handed out. Deterministic, not cryptographic.

Common use cases

• A times-table starter that asks children to read numbers rather than recite them
• A printable filler for a maths lesson, a cover lesson or a homework sheet
• Number recognition practice for a younger class, using three-digit numbers
• A puzzle page for a school newsletter
• Setting the same sheet for two classes by sharing the seed

How this generator works

Numbers are placed longest first, crossing where their digits agree, and the remaining squares are filled with digits weighted towards the ones the numbers themselves use. The finished grid is then scanned in every allowed direction, and any occurrence the key does not list is rewritten away. Where that cannot be done — an accidental number lying entirely inside two crossing numbers leaves no filler square to change — the grid is discarded and another built, up to eight times. Measured over forty grids in every offered combination, none was published carrying an unlisted occurrence.

Randomness and fairness

The numbers, their placement and the filler all come from your browser's cryptographic random source unless you type a seed. A seed is for reproducibility, not cryptographic strength: it brings back the identical sheet, and anyone with it can do the same.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

• Two-digit numbers are not offered. In a grid of ten digits they turn up by accident everywhere — measured at up to 121 unlisted occurrences on a single twelve-square grid — and no answer key could be honest.
• Backwards numbers are offered only with four-digit numbers, for the same reason at a smaller scale.
• A times table starts at a hundred rather than at the beginning, so the first few multiples of a small table never appear.
• Numbers are not laid out for print on a particular paper size; the grid is drawn for the screen and copied as text.
• Difficulty is a matter of directions and grid size only; the puzzle is not graded.

Privacy and your data

The list, the grid and the check all run in your browser. Nothing you choose or type, and no sheet built from it, leaves the device.