Odd one out
Five figures, and four of them share something the fifth doesn't. Here's how to find what they share, one feature at a time, and how to answer most like questions too.
Chapter 1
What are odd one out questions?
You’re shown five figures: pictures in boxes, numbered 1 to 5. Four of them share something that the fifth doesn’t. That fifth one is the odd one out, and it’s your answer.
Rush asks it two ways, both with five options like the exam. In Doesn’t Belong you find the odd one out. In Most Like you’re shown three figures that share something, and you pick the option that shares it too.
Which one doesn't belong?
An NVR question from Rush, level 1.
Your checklist: eight features
Every figure is built from these. Check them one at a time, across all five figures.
- Shape and sides
- Shading
- Outline
- Size
- Where it points
- Shape inside
- Dots and lines
- Corner shape
Chapter 2
Solve it in 3 steps.
Here’s the question, one feature at a time.
The question
Which one doesn't belong?
An NVR question from Rush, level 1.
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Step 1
Read one feature across all five.
Start with the shape: a pentagon, a triangle, a heart, a triangle, a circle. No four match, so the shape isn’t the rule. The shading: dotted, white, striped, striped, white. No four match there either.
No four shapes match.
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Step 2
Three and two is not a rule.
Three have a dashed outline and two don’t. Three are big and two are small. The shape inside, the lines on top and the corner shape split three and two as well. A rule needs four the same, so keep going.
Three dashed, two not: keep going.
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Step 3
Stop when four match and one doesn’t.
Count the dots: 4, 4, 4, 2, 4. Four figures have four dots, and option 4 has only two. That’s four and one, so it’s the rule.
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Three mistakes it sets
| The mistake | Do this instead |
|---|---|
| Picking the one that looks oddest. Option 3, the small striped heart on its side, catches your eye. But it has four dots, like three of the others. | Run the checklist before you choose. |
| Picking the only one of something. Option 1 is the only pentagon and option 5 the only circle. But the other four don’t share one shape, so that isn’t a rule. | Look for what four share, not what one has. |
| Taking three and two as the rule. Options 2 and 3 are the only ones without a dashed outline. That makes two odd ones, and there’s only ever one. | Keep going until four match and one doesn’t. |
So it’s option 4. The other four all have four dots under them. The striped triangle has two.
Remember: One feature across all five.
Chapter 3
The catches.
Doesn’t Belong asks four other ways. Each card gives the rule, an example and the trap.
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12345
Four turned, one flipped
Turning never flips a shape. Find the one that’s back to front.
Stand each one up in your head, foot at the bottom. In four, the foot points right. In option 3 it points left: it’s flipped. Trap: option 3 looks like an L upside down, but an L upside down is option 5.
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12345
Which shape is on top?
Look where the outlines cross.
In four, the black shape lies on top of the white ones. In option 4 the white triangle and circle lie over the black square: it’s underneath. Trap: which shape is black changes freely. It means nothing.
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12345
Columns: read them as lists
Say each column’s shapes, top to bottom.
Four say diamond, pentagon, square. Option 2 says diamond, square, pentagon: two shapes have swapped. Trap: the black and white change from column to column. They mean nothing.
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12345
No feature works? Compare the parts
Compare the parts inside each box with each other.
The shapes and shading change freely, so the checklist finds nothing. But in four, both parts are shaded the same. In option 5 they aren’t. Other links: a small copy of the big shape, a matching pair, one shape inside the other.
Chapter 4
Most like: turn it round.
Three figures share something. Pick the option that shares it too. The checklist still does the work.
Which one belongs with these three?
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Step 1
List what all three share.
Go down the checklist for the three. All three are striped. All three have 2 lines on top. That’s your list.
Striped, with 2 lines on top.
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Step 2
If it changes, it isn’t the rule.
The shape, the size, the outline, the shape inside, the corner shape and the dots all change from one to the next. The dots go 1, 3, then none. Ignore all of these.
130The dots change, so they can’t be the rule.
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Step 3
Find the option with everything on the list.
Options 2 and 4 aren’t striped: out. Options 1 and 5 have 3 lines and 1 line on top: out. That leaves option 3. Options 1, 2 and 4 are lookalikes, each drawn like one of the three but missing something on the list.
12345
So it’s option 3. It’s striped with 2 lines on top, like all three, even though it looks the least like them.
Remember: If it changes, it doesn’t matter.
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Nothing shared? Link the parts
Compare two parts of each figure.
The shapes, shading and dots all change. But each figure has as many dots as sides, so the diamond fits. Another link: the same shape inside as outside. Trap: the triangle with 4 dots, which has only 3 sides. Doesn’t Belong uses these links too.
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Wheels: read them clockwise
Start at the same symbol each time, and go clockwise.
From the triangle, all three go square, diamond, circle, just turned round. The ringed option keeps that order. The crossed one runs it backwards: a mirror image. Trap: two symbols swapped, or a shading changed.
Chapter 5: In the exam
A rule Rush doesn’t use.
Exam figures can be busier, and some papers use a rule Rush never does: symmetry. Add it to the end of your checklist.
Which is the odd one out?
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Step 1
Run the checklist.
The shapes are all different. The shading goes black, striped, white, black, striped. The sides go 7, 4, 5, 4, 3. Nothing splits four and one.
A 7B 4C 5D 4E 3Sides: no four match.
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Step 2
Then try a fold.
Can you fold each one so its two halves match? The arrow folds along its slant, the kite across, the house and the triangle down the middle. The parallelogram can’t: whichever way you fold it, the halves never match, though it looks as if they should.
ABCDEFour fold. D doesn’t.
So it’s D. The other four all have a line of symmetry. The parallelogram has none.
Remember: No split? Try a fold.
Other ways the exam asks it
- Most like with two figures. Some papers give two, not three. More things match by chance, so check each one against the options: the answer has everything both share.
- Turned, not flipped. Three copies of one shape at different turns. The answer is another turn, and the wrong ones are often mirror images.
- Links that count. The shape inside has as many sides as the outline, or the number of small shapes matches the sides. Count both parts.
Chapter 6
Try it yourself.
Six real questions from Rush, easy to hard, 60 seconds on the clock.
Use the steps
- Read one feature across all five.
- Three and two is not a rule.
- Stop when four match and one doesn’t.
Remember: One feature across all five.
For parents.
What parents ask us about odd one out.
Questions parents ask
How do you do odd one out in non-verbal reasoning?
Find what four of the five figures share, then pick the one without it. Check one feature at a time (shape, shading, outline, inside shape, dots, lines, corners) and stop when one splits four and one.
Why does the answer sometimes look the most normal?
Because the odd one out only has to differ in one feature, often a small one such as the number of dots. Trust the four-and-one count over your first impression.
What are non-verbal reasoning similarities questions?
They're odd one out the other way round. You see a set of figures that share something, and pick the option that belongs with them. They’re often called ‘most like’ questions. The method is above.
Do I need to know shape names?
It helps to know pentagon, hexagon, heptagon and octagon, to count sides quickly and to spot a line of symmetry. Some rules compare the number of sides with the number of dots or with the shape inside, and in some paper questions the answer is the one figure that isn't symmetrical.
Rush: 11+ Practice & KS2 SATsPractise odd one out in Rush.
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