UCAT DM Logic Puzzles: How to Set Up the Grid in 30 Seconds

There are roughly four logic puzzles per UCAT Decision Making (DM) paper. With 31 minutes for 35 questions, you have about 53 seconds per item on average, but logic puzzles legitimately deserve closer to 90 seconds because the setup work pays off across two or three sub‑questions.

The students who blow up on DM almost always do the same thing:

Read the four clues
Hold them in working memory
Scan the answer options
Re‑read the clues
Repeat

By the third re‑read, two minutes are gone and nothing is on the whiteboard.

A grid kills that loop. Done properly, it takes ~30 seconds. After that, the puzzle is mostly pattern matching.

This post shows you exactly how to set up that grid, when to use it, and how to avoid the common mistakes that cost marks.

Why grids beat re‑reading the question

On screen you see:

4–5 clues
A list of entities (people, items, positions)
One or more questions

Your working memory can hold maybe 3 chunks of information before the next one pushes something out. So you re‑read. And re‑read. The clock keeps ticking.

A grid externalises working memory onto the whiteboard. Once a constraint is on paper as a tick or a cross, it stops occupying brain space. You can now reason about combinations instead of trying to remember whether Alex sits to the left or the right of Bo.

If you time yourself on the UCAT Consortium’s official practice tests at ucat.ac.uk, the difference is obvious:

With grids: you finish the logic puzzles with time to spare.
Without grids: you hit the 31‑minute wall around question 28, having re‑read the same clues multiple times.

The whole strategy is:

Pen on the laminated whiteboard, eyes on the screen, brain doing one thing at a time.

Choosing rows and columns from the clues

The first decision is what goes on the axes. Get this wrong and you waste 20 seconds rebuilding the grid. Get it right and the rest is mechanical.

Rule of thumb:

Rows are the fixed set, columns are the variable being assigned.

Example: “Five friends each ordered a different drink.”

Friends are fixed (you cannot add or remove them) → rows
Drinks are the variable being matched → columns

So you draw a 5×5 grid: friends down the left, drinks across the top.

When there are three categories

If you have three categories (e.g. friends, drinks, seating positions), you need either:

A 3‑axis grid (awkward on a small whiteboard), or
Two stacked grids (faster and cleaner):
- Friend × Drink
- Friend × Position

You then cross‑reference between them when a clue links two non‑friend attributes, e.g. “the person who ordered coffee sat at the end”.

Quick heuristics for picking the primary axis

Use these to decide what goes where in under 5 seconds:

The category with named entities (Alex, Bo, Cara) usually goes on the rows, because clues reference them by name.
The category being asked about in the question stem often goes on the columns, so your finished grid answers the question directly.
If clues reference positions or order (left of, between, next to, first, last), positions deserve their own axis, even if that means drawing a second grid.

Setup budget:

5 seconds: skim clues, identify categories
10 seconds: draw a 4×4 or 5×5 box
10–15 seconds: label rows and columns

That’s your 30‑second grid setup.

Marking certainties vs eliminations

Use two symbols only:

Tick (✓) for certainty
Cross (×) for elimination

Never write words in cells. Words are slower to write, harder to erase on laminated boards, and clutter the grid.

Direct matches

When a clue gives you a direct match, e.g.:

“Cara ordered the latte.”

Do this immediately:

Tick the Cara–latte cell.
Cross out the rest of Cara’s row (she did not order anything else).
Cross out the rest of the latte column (no one else ordered the latte).

In a 4×4 grid, that single tick eliminates 7 other cells. This cascading elimination is where the grid earns its keep.

Conditional clues

For a conditional, e.g.:

“If Bo had the espresso, Alex had the tea.”

Do not mark the grid yet. Instead:

Note the conditional in the margin with a small arrow, e.g. Bo = espresso → Alex = tea.
Only come back to it once another clue fixes Bo’s drink.

Order of operations for clues

Work clues in this order:

Direct matches first — anything of the form “X is Y”.
Direct exclusions next — anything of the form “X is not Y”.
Relative clues third — “to the left of”, “two seats apart”, “more expensive than”.
Conditionals last — these usually resolve themselves once steps 1–3 are done.

This order prunes the search space before you tackle the messy logic. Many puzzles collapse after steps 1 and 2 alone.