Number Grid
Hard
00:00
Classic
About hard number grids
The grid grows to 4×4, which means eight equations (four rows, four columns) and sixteen cells inside the grid holding each of the numbers 1 to 16 exactly once. More importantly, some of the operation cells are blank too. You need to figure out not just which number goes where, but which operation connects them.
The good news: usually only one or two operations produce an integer result with the surrounding numbers. Try each mentally. If multiplication gives 37.5 but addition gives 15, addition is the one. This trial-and-error on operations is the main new skill at hard difficulty.
This level is aimed at older students (grades 5–8) and adults who want a moderate workout. If you are breezing through, head to expert.
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.