Concept 9 of 9
Spot the Odd Figure: A Turn or a Missing Part
Today's big idea
Count the parts first, then check the facing, because a turn survives any count.
Turning changes no count, so once parts match, look for the odd facing.
How it works
👀 What's going on?
In a spot-the-odd-figure puzzle, four shapes are almost identical and just one is different. Sometimes the odd one has quietly turned to face another way, and sometimes a small piece has gone missing. Neither is as obvious as an extra part stuck on, so you have to look carefully.
💡 Here's the trick
Look at the five arrows above. Every one of them is the same arrow, the same size and the same colour, so counting parts finds nothing. The fourth one is facing a different way. Orientation is a feature too, and it is the one people forget to check.
🪄 How to do it
- 1.Count the parts across the row first, as the arrows above all have one head.
- 2.If the counts agree, check which way each figure faces.
- 3.If both agree, look for a small piece present on most and missing on one.
✍️ Try it
Five combs each have five teeth, except one has four. Then five identical shapes, one of which has been turned a quarter turn.
Counting teeth finds the comb with four, because a missing piece shows up in a count. The turned shape does not show up in any count at all, and only a check of which way each one faces finds it.
⚠️ Watch out
You might be thinking a turned figure is still the same figure, so it cannot be the odd one. In these puzzles it can. If four face one way and one faces another, the one is the answer.
🌟 Why this matters
Checking a part is fitted the right way round, or that nothing is missing from a set, is the same careful sweep. Both errors hide from a quick glance.
Exam tip: Run the count first and the orientation second, because counts are quicker.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Five figures look alike. Four are identical and one has been turned. Which check finds it?”
- 1
Try counting first
A turn adds nothing and removes nothing, so every count still agrees.
- 2
So counting cannot find it
A turn is invisible to any tally of parts.
- 3
Check the facing instead
Four point one way and one another, the only feature that differs.
- 4
Answer ✓
compare which way each one faces
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Count the parts first, then check which way each one faces.
TURN SPOTTER · ROUND 1 OF 3
Step 1 · will counting parts find it?
Quick check
✅ VERIFICATION
Five figures look alike. Four are identical and one has been turned. Which check finds it?
⚡ Finish the activity above first to answer.
Keep going!