Concept 4 of 6
Number & Letter Analogies
Today's big idea
Read the rule that turns A into B, then carry that same instruction across to C.
Rules that fit only the first pair are what the wrong answers are built from.
How it works
👀 What's going on?
Numbers and letters make analogies too, and these are the ones children rush. The pair looks small enough to guess, so the rule never gets said out loud and the guess goes in.
💡 Here's the trick
Look at the pairs above. 2 goes to 4 by doubling, so 3 goes to 6 the same way. D goes to F by stepping two letters on, so G goes to I. The link is always an instruction you can carry across unchanged.
🪄 How to do it
- 1.Look at the pairs above and work out what turns A into B.
- 2.Say the rule as an instruction, such as double it, or move on two letters.
- 3.Carry out that same instruction on C.
✍️ Try it
Work out 5 : 10 :: 7 : ? Then try M : P :: B : ?
Five doubles to ten, so seven doubles to 14. M to P is three letters on, so B moves on three letters to E.
⚠️ Watch out
You might be thinking the first rule that works is the right one. Take 9 : 3, which could be take away six or divide by three. Only one of those also turns 12 into 4, so test your rule on the second pair before you trust it.
🌟 Why this matters
Spotting the instruction hidden inside a pair is the same move as spotting what comes next in a run of numbers. It is reading a rule off an example, which is most of what reasoning is.
Exam tip: A rule that fits only the first pair is the commonest wrong answer in this topic.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“2 : 4 :: 3 : ?”
- 1
Find the link A → B
2 → 4 means multiply by 2. Rule = ×2.
- 2
Say the rule out loud
“B is double of A.”
- 3
Apply the rule to C
3 × 2 = 6
- 4
Answer ✓
? = 6
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
A is to B as C is to ? — tap a rule to test it on 3. The right rule turns 3 into 6.
ANALOGY · ROUND 1 OF 3
Quick check
✅ VERIFICATION
In 20 : 5 :: 16 : 4, which rule works on both pairs?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Object-Use Analogies
What do you do with the object? That's the link.