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Logic grid

Three to five people, each with a different pet, drink or home town. From a handful of clues, work out who has what.

  • Logic
  • Untimed
  • 8 levels

How it plays

Each person has exactly one of each kind of thing — one pet, one drink — and no two people share one. The clues say who has what, who does not, and what goes with what. Answer the one question asked.

A grid on paper helps: people down the side, things across the top, a cross for every “does not”. When a row or a column has one gap left, that gap is filled.

Levels add people and kinds of thing, and lean more on what people do not have, which takes more steps. Every puzzle has exactly one arrangement that fits, checked by trying them all, and no clue you could do without.

Keys

Space starts and skips ahead · 1–9 pick · Enter submits · Esc stops. On a phone, tap.

What it trains

This practises elimination — tracking what is ruled out until one possibility is left — on grids like these. It claims nothing wider.

Learn

How to get better at logic grid: the method, the techniques, what each new level asks of you, and the traps the wrong answers are made of.

Your approach to each question

  1. Read the question first. You need one fact — which pet Bilal keeps, or who is from Goa — and you can stop as soon as you have it.
  2. Draw the grid: people down the side, each kind of thing across the top, and one box between every two kinds of thing too — pets against drinks, as well as people against each.
  3. Enter the direct clues: a tick for “Asha keeps the cat”, a cross for “Asha does not drink tea”. After every tick, cross out the rest of that row and column in its box.
  4. Then use the linking clues — “the person who keeps the cat drinks tea” — to copy ticks and crosses from one box to another, and look for rows or columns with one gap left.

Techniques and tricks

  • One gap left is a tick

    Each person has exactly one of each thing, and no two share. So when every cell but one in a row is crossed, the last is a tick — and the same for a column.

    e.g. Three people, three pets: Asha does not keep the cat, Bilal does not keep the cat. So Chen keeps the cat.

  • A tick crosses its whole line

    Once Asha keeps the cat, nobody else keeps the cat and Asha keeps nothing else. Cross both lines at once; most new gaps come from this.

  • Carry ticks through a link

    A linking clue joins two things as one person. If the cat-keeper drinks tea and Asha keeps the cat, Asha drinks tea. Whatever is true of one is true of the other.

  • Carry crosses through a link

    A link carries crosses too. If the dog-keeper drinks tea and Asha does not drink tea, Asha does not keep the dog. It is the easiest move to overlook.

    e.g. “The person who keeps the dog drinks tea.” “Asha does not drink tea.” So Asha does not keep the dog.

  • A negative link splits two things

    “The person who keeps the cat does not drink tea” puts a cross in the pets-against-drinks box. Then anyone who drinks tea does not keep the cat, and anyone who keeps the cat does not drink tea.

  • Count the crosses per person

    With n people, a person needs n − 1 crosses in a kind of thing to be settled. Count where you are close, and look for the clue that gives the last one.

As the levels climb

  • The grid grows in a fixed order — 3 people with 2 kinds of thing, then 3 with 3, 4 with 2, 4 with 3, 5 with 2, 5 with 3 — up to the “Most people” setting. Early on, each growth alternates with a change in the clues.
  • The clues lean more and more on what people do not have: the share of “does not” clues drawn rises from about a quarter to nearly half, then about two in three. Negative clues take more steps, so the gap-counting does most of the work.
  • A third kind of thing means three more boxes in your grid, and linking clues can run between any two kinds. Draw every box, not just the ones with people.
  • With “Time pressure” on, the clock gives 30 seconds plus 12 for each clue. More clues bring more time, but each clue must still be entered once and used fully.

Traps to avoid

  • The option no clue mentions: the wrong options are chosen first from the ones that no single clue rules out, so they look possible on a first read. Only a finished line in your grid settles it.
  • Reading a link as a name: “the person who keeps the cat drinks tea” does not say who that is. Keep it as a link between the cat and tea until a clue names the person.
  • Answering the other way round: “Who keeps the parrot?” wants a name; “Which pet does Dara keep?” wants a pet. Check which one the options are.
  • Forgetting that no two share: once someone has the tea, everyone else lacks it. Missing that cross is how a grid stalls with the answer already there.

How to practise

  • Set “Most people” to 3 and solve on paper with a full grid until entering clues is automatic, then raise it to 4 and 5.
  • Raise “Options shown” to 5: with every person or thing on offer, only a finished line in your grid picks the answer.
  • After a miss, read the full table in the working and find the first clue you used wrongly or not at all.

Levels

It is untimed unless you turn the clock on. There are 8 levels with the default settings, and the counter stops at the real top. Your level is judged on your last ten answers, every ten: 90% moves you up, below 80% moves you down, which holds most people near four in five right.

All of it is in the settings beside Start — how many answers a judgement looks at and how often it recalibrates, the thresholds, the time, which questions, how many options, and whether you see each verdict at once or review them together at the judgement. You can also jump to any level.

More logic

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