Count the sides, then the dots
Each number says how many of its square's four sides the loop uses. Each dot on the loop has exactly two lines, and a dot the loop skips has none. Use the numbers first, then the dots.
The 0 in the middle has no lines, so all four of its sides get an X. Each 3 next to it has lost the side it shares with the 0, so its other three sides are lines.
Now look at the four corners of the 0, circled in the drawing. At each one, one line arrives and only one side is still open, so the line has to go that way. A line never stops at a dot.
Two more dot rules finish most boards. When two lines already meet at a dot, mark its other sides X, because the loop never branches. When a dot has no line and only one open side, mark that side X too: a line there would have nowhere to go.
Do not close the loop early
Keep counting and the path grows around the board until its two loose ends sit at the two ends of one side: the left side of the 3 on the right.
Drawing that side would close the loop, and it looks finished. But a closed loop cannot grow any more, and that 3 would have one line instead of three.
So that side gets an X. Then the 3 has three open sides left and needs all three, so the loop goes around it, and every number is met.
Before you close a loop, check every number on the board. If one is still short, the closing side is an X.
A 3 in a corner
This board has a 3 in its top left corner. The dot at the very corner of the board has only two sides: the top and the left side of that square.
Remember the rule at every dot: two lines or none.
Try it
Which two sides of the corner 3 must be lines?
- Its top and its left side
- Its right and its bottom side
Show the answer
Its top and its left side
Correct. The 3 uses three of its four sides, so it uses its top or its left side, or both. The corner dot has only those two sides, and a line cannot stop there, so both are lines.
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Practice Make one loop