Puzzle guide
How to solve Hidato
Hidato is a trail of numbers. You count from 1 to the last number, and each step goes to a cell that touches the one before, at a side or at a corner. Some numbers are already on the board; your job is to fill in the trail between them.
The rules
- Fill every empty cell with the missing numbers, 1 to the last, continuing the trail the given numbers start.
- Each number touches the one before it and the one after it: at a side or at a corner.
- Every number is used exactly once, and every cell on the board is part of the trail.
A solved puzzle
Your first moves
- Find the 1 and the last number. They are the two ends of the trail.
- Look for gaps: between a given 4 and a given 7 there are exactly two numbers, 5 and 6, and they have to fit in between.
- Follow the trail from every given number: if only one empty cell touches it, the next number goes there.
- Count steps: a number can only be as far from another as their difference allows.
Techniques, step by step
Follow the trail
The 4 in the corner needs a 5 next to it. Its neighbours are the 3, the 7 and one empty cell. The 3 and the 7 are taken, so the 5 goes in the empty cell. This is the move you make most often: from every number, look at its free neighbours, and if there is only one, write the next number there.
The only cell for a number
The 3 has to touch both the 2 and the 4. Two cells touch both of them, but one is already taken by the 8. So the 3 has exactly one cell left. Whenever a missing number sits between two given ones, look for the cells that touch both.
The only number for a cell
Turn the question round: take an empty cell and ask which numbers could go there. A cell in a corner, far from most givens, may touch only one stretch of the trail. If only one missing number can reach it, that number goes there. Players often find this move last, so it is worth checking when you are stuck.
Too far to reach
A number can be at most as many steps away from another as their difference. From a given 10, the 12 is at most two steps away, so any cell three or more steps from the 10 cannot hold 11 or 12. Striking those cells out often leaves a number with just one place. This is the idea that solves the harder, emptier boards.
Fill the gaps exactly
Between a given 5 and a given 9 there are three missing numbers, so the trail between them takes exactly four steps. If the two are four steps apart in a straight line, the trail can only go straight. If they are closer, it must wind. Counting the length of each gap tells you how much room the trail needs.
Common mistakes
- Forgetting diagonals. Consecutive numbers may touch at a corner. Diagonal steps are often exactly what is missing.
- Leaving a cell out. Every cell is part of the trail. A cell nobody can reach any more means an earlier step is wrong.
- Cutting off a corner. Watch empty corners: if the trail passes by without entering, the corner can never be filled.
- Trusting a board with no warnings. The app marks only two numbers in a row that are too far apart. Empty cells are not marked.
Questions and answers
Ready to play?
Follow the trail, look for the one cell a number can take, and count how far each step can reach. That is how a Hidato trail joins up from 1 to the end.