Small steps. Big discoveries.
Number puzzles / ages 9–12

Sum Mesh

A little logic. A few sums. A lovely moment when it clicks.

Take your time 🌱
Choose a square, then use the number pads to explore.

↓ Add down   ·   → Add across   ·   Stop at a green square   ·   Grey digits are starting clues. A brighter green clue means that total matches; crossing sums still need to agree.

Original puzzles · No timer · No repeated digits within a single sum

Every sum has a story.

Fill the white squares with digits 1 to 9. Each green clue belongs to the white squares immediately beside it: → add across, ↓ add down. Stop at the next green square or the edge. Some green squares contain two clues, one for each direction.

No repeated digits within each separate sum. A digit can appear in another sum, even in the same row or column.

Select a white square. Use the small pencil pad to record possibilities such as 8 and 9. When you decide, use the large answer pad: your answer replaces those notes.

Grey digits are helpful starting clues. Try the smallest totals first. For example, two different digits adding to 3 must be 1 and 2.

Keyboard: arrows move between squares; 1–9 enter answers; Shift + 1–9 toggles notes; Backspace erases. Your progress is kept while switching levels.