Solving Number Place puzzles in Games by Zaweba

Number Place is the 9 by 9 number grid that fills newspaper puzzle pages, and it is one of the most popular games on the Puzzles shelf of Games by Zaweba. Each puzzle starts with some numbers already in place. You fill every empty cell so that each row, each column and each of the nine 3 by 3 boxes holds the digits 1 to 9 exactly once.

Every puzzle has just one answer, so it can always be reached by logic.

Entering numbers

With the mouse, click a cell and then click a number on the pad. On the keyboard, use the arrow keys to move round the grid and press 1 to 9 to enter a number. Backspace erases a cell. Many people find the keyboard faster once they are used to it, especially for the notes described below.

Pencil notes

Press P to switch to notes. In notes, the numbers you enter go into the cell as small pencil marks rather than as answers. This is how to keep track of possibilities. If a cell could be a 3, 5 or 8, pencil those in, and come back to it as the rest of the grid fills up.

Notes are what make harder puzzles manageable. Without them, you have to hold dozens of possibilities in your head. With them, you can see at a glance where a number can only go in one place.

How the score works

Your score is your time, plus 20 seconds for each mistake and 30 seconds for each hint. Lower is better. That makes it a race against the clock, but one where care counts too: a guess that turns out wrong costs you more than a moment of thought.

Press H if you need a hint, and Z to undo. Undo is not one of the penalties, but a hint carries its 30 second cost, so it is worth looking round the grid once more before asking.

A way into any puzzle

Start with the simplest method. Pick a number, say 1, and look at each box in turn. Using the 1s already placed in the rows and columns around it, see whether the box has only one cell where a 1 can go. If it does, place it. Go through all nine digits like this and a good part of an easy puzzle will fall into place.

Then switch to cells. Look for a cell where eight of the nine digits already appear in its row, column and box. The ninth must go there.

When those stop working, fill in notes for a row or box and look for pairs. If two cells in a box can only be 4 or 7, no other cell in that box can be 4 or 7, which often frees up the rest.

Number Place in the app

Number Place sits on the Puzzles shelf of Games by Zaweba with Picture Grid, Hidden Mines and Colour Code, the logic puzzles that reward careful deduction. Games by Zaweba keeps your best result for each mode and how often you have played. Press Esc to pause in the middle of a puzzle, F11 for full screen, and F1 if you want the rules explained.