Number Grid
About easy number grids
A3×3 grid with six equations — three horizontal, three vertical. Only addition and subtraction. The nine cells inside the grid hold each of the numbers 1 to 9 exactly once, the way a sudoku box does, and between one and four of them are blank.
Because each equation is short (number-operation-number-equals-result), you can usually solve a blank by reading the equation it belongs to. If the row says 5 + ? = 8, the answer is 3. Check the column for that cell and you will often find another freebie. When a blank sits in a row and a column whose totals are both missing, the arithmetic alone will not settle it — then look at which of 1 to 9 is not on the board yet. These are good warm-ups and a solid starting point for kids in grades 2 or 3 who are practicing their addition facts.
Once easy grids feel automatic, move to medium — same 3×3 size, but multiplication enters the picture.
How to play Number Grid
- Every row is an equation read left to right, and every column is one read top to bottom. Its answer sits at the end of the line — down the right-hand side, along the bottom.
- The arithmetic is the ordinary kind: × and ÷ are settled before + and −. So 2 + 3 × 4 is 14, not 20.
- Division always comes out exact. A value that would leave a fraction is the wrong value.
- The numbers you write INSIDE the grid come from a fixed pool, each used exactly once — the way a sudoku uses its digits. Easy and medium use 1 to 9, hard 1 to 16, expert 1 to 25, and einstein uses −12 to −1 and 1 to 24, with no zero.
- That pool is often the only thing that settles a cell. A blank whose row answer and column answer are both blank is pinned by nothing else — the arithmetic would take any number at all.
- The answers round the edge are NOT part of the pool. They are totals: whatever the arithmetic makes them, and they may repeat.
- From hard upward some of the round operation cells are blank too, so you work out the sign as well as the number.
- Every puzzle has one solution, reachable by logic alone.