Basics
Thermometers is a logic puzzle: the grid is covered with thermometers and you work out how far the mercury has risen in each of them.
- A thermometer fills from its round bulb towards the tip, cell by cell with no gaps.
- A thermometer can be empty, partly filled or completely filled.
- The number next to a row or column shows how many cells in that line are filled.
- The puzzle has one solution, and it can be found by reasoning alone, without guessing.
Bulb — the start of a thermometerFilled cellEmpty cell
Worked example
Let’s solve a 4×4 grid. First look for lines where the answer is obvious — a zero or a number equal to the line length — then work out the rest.
Find the strongest numbersOn an empty grid, 0 and a number equal to the line length tell you the most: the second row is marked 0 and the third is marked 4.
Step 1 of 6
Interactive lesson
Step 1 of 54 min
Technique · mercury from the bulb
Mercury rises from the bulb
A thermometer fills cell by cell starting from its round bulb, with no gaps. In the top thermometer the mercury has reached the second cell. How many of its cells are filled?