Concept 2 of 7
Odd One Out: Spot the Misfit
Today's big idea
Name what three of them share, and the fourth one names itself.
Name the property most of them share; the one that lacks it is the misfit.
How it works
👀 What's going on?
Four items, and one of them does not belong. The instinct is to stare at each one hunting for something odd. That is the slow way round.
💡 Here's the trick
Look at the four shapes above. Rather than examining the circle, name what the other three share: every one has straight sides. Once you can say the shared property out loud, the misfit names itself. Find the group first and the odd one falls out.
🪄 How to do it
- 1.Look at all four items together, as the picture above lays them out.
- 2.Ask what three of them have in common, and say it out loud.
- 3.Whichever item lacks that property is your odd one out.
✍️ Try it
First take 3, 5, 9 and 11. Then take cow, goat, tiger and sheep. What do three of each share?
Among the numbers, 3, 5 and 11 are all prime while 9 is 3 x 3, so 9 is the misfit. Among the animals, cow, goat and sheep are all kept on farms, so tiger is the misfit. Naming the group made both of them obvious.
⚠️ Watch out
You might be thinking there is only ever one way to group four things. Sometimes two properties both work, and then the odd one changes. Pick the property that leaves exactly three together, because that is the one the question means.
🌟 Why this matters
Sorting the odd sock out of a pile. Spotting the ingredient that does not belong in a recipe. Both of them use this. Naming what the rest share is the whole move.
Exam tip: Say the shared property out loud in your head, because a property you cannot put into words is usually not the intended one.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Odd one out: 15, 21, 33, 40.”
- 1
What 3 share
15, 21, 33 are all in the 3 times table.
- 2
The misfit
40 is not a multiple of 3.
- 3
Answer ✓
40
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Tap the three that belong together to drop them in the basket. The one left behind is the misfit.
SORT · ROUND 1 OF 3
Quick check
✅ VERIFICATION
Odd one out: Apple, Banana, Carrot, Mango.
⚡ Finish the activity above first to answer.
Keep going!
Up next: Classification
Pick a property, sort items into buckets, count each bucket.