Puzzles — The Grid Method for Day, Floor and Person Puzzles

A puzzle gives you several people and several attributes — days, floors, colours, subjects — and clues that link them. The grid method turns it into simple elimination.

1. The grid

• Rows = people. Columns = the attribute (days, floors…).
• ✓ = definitely true, ✗ = impossible.
• Each row and each column has exactly one ✓ (when everyone gets a different value).
• When a row has one ✓, cross out the rest of that row and that column.

2. A full example

Four friends — Asha, Bilal, Chetan and Divya — each have an interview on a different day, Monday to Thursday.

1. Chetan's interview is on Monday.
2. Asha's interview is the day after Chetan's.
3. Bilal's interview is not on Thursday.

Solve:

• Clue 1: Chetan = Mon ✓ → cross out Mon for everyone else.
• Clue 2: Asha = Tue ✓ → cross out Tue for Bilal and Divya.
• Bilal and Divya are left with Wed and Thu (the "?" cells in the picture).
• Clue 3: Bilal ≠ Thu → Bilal = Wed, Divya = Thu.

Answer: Mon Chetan, Tue Asha, Wed Bilal, Thu Divya.

3. Floor puzzles

Floors are like a vertical row. "Above" and "below" are like "right" and "left".

Example

Five people live on floors 1 (bottom) to 5 (top) of a building, one per floor. Kiran lives on floor 3. Mohan lives just above Kiran. Leela lives on the top floor. Nisha lives below Omar. Who lives on floor 1?

• Kiran 3, Mohan 4, Leela 5.
• Floors 1 and 2 are left for Nisha and Omar. Nisha is below Omar → Nisha 1, Omar 2.

4. Two attributes at once

When each person has two attributes (e.g. a day and a city), use a table with one row per person and one column per attribute. Fill it as you go:

Clues like "the person going to Pune goes on Wednesday" link the columns; write them next to the table until you can place them.

The order to read clues

1. Definite clues ("X is on Monday").
2. Relative clues that touch a placed person ("Y is the day after X").
3. Negative clues ("Z is not on Thursday") — use them to eliminate.
4. If stuck, branch: take one open cell, try both values, and see which one breaks.

Common mistakes

• Not crossing out the column after placing a ✓.
• Reading "between" as "immediately between".
• Writing too little: draw the grid even if the puzzle looks small.

Quick recap

• Grid of people × values; ✓ and ✗.
• One ✓ per row and column → cross out the rest.
• Definite → relative → negative clues → branch if stuck.