Analogies and Classification
Complete word and number analogies, and identify the odd one out in a group.
What you'll learn
- Identify the relationship between a pair of words or numbers in an analogy
- Apply that relationship to complete a second pair
- Find the item in a group whose category differs from the rest
Prerequisites
Explanation
An analogy asks you to find the relationship in one pair (A is to B) and apply that same relationship to complete a second pair (C is to ?). Relationships come in recognizable types: part-to-whole (Page : Book), function (Hammer : Carpenter, a tool and who uses it), cause-effect, opposites, or a numeric rule (multiply, add, square).
Take 2 : 4 :: 3 : ?. The relationship between 2 and 4 could be "multiply by 2" (giving 6) -- and since 4 is exactly 2 times 2, that's the simplest consistent rule, so the answer is 6. Compare that with 2 : 5 :: 10 : ?: here 5 is not a clean multiple of 2, so the relationship is more likely additive ("add 3"), giving 10 + 3 = 13. The key skill is testing whether the first pair's relationship is multiplicative or additive before assuming which one applies.
Classification (also called "odd one out") gives you a group of items and asks which one doesn't share the category the others do. Triangle, Square, Pentagon, Circle -- three are polygons with straight sides and vertices; a circle has neither, so it's the odd one out. The trick is identifying what specific property the majority shares, not just guessing which one "feels" different.
Both skills share a common discipline: state the rule explicitly before applying it. "These three are all fruits, this one is a vegetable" is a testable claim; "this one just seems different" is not, and it's exactly the kind of vague reasoning that leads to a wrong answer under time pressure.
Example
Completing a numeric analogy by detecting a multiplicative or additive relationship.
function completeAnalogy(a, b, c) {
if (b % a === 0) return c * (b / a);
return c + (b - a);
}
// completeAnalogy(2, 4, 3) -> 6 (relationship: multiply by 2)Guided exercise
Guided exercise
Write findOddOneOut(words, groupOf) where groupOf maps each word to its category. Return the word belonging to the minority category, or null if every word shares one category.
Checks: Finds the minority-category word · Works with a different category pairing · plus 1 hidden check
Code editor. Press Escape then Tab to leave the editor if keyboard focus becomes trapped. Press Control+Shift+M inside the editor to toggle Tab-key focus trapping.
Stuck? Get a hint.
Independent exercise
Independent exercise
Write completeAnalogy(a, b, c) that detects whether b relates to a by multiplication (when b is an exact multiple of a) or by addition, and applies that same relationship to c, returning the result.
Checks: Applies a multiplicative relationship · Applies an additive relationship · plus 1 hidden check
Code editor. Press Escape then Tab to leave the editor if keyboard focus becomes trapped. Press Control+Shift+M inside the editor to toggle Tab-key focus trapping.
Stuck? Get a hint.
Common mistakes
- Assuming a numeric analogy is always additive, or always multiplicative, without testing which fits the first pair.
- Picking an odd one out based on a vague feeling instead of naming the shared category explicitly.
- Overlooking that a word analogy can be based on function or cause-effect, not just simple similarity.
Knowledge check
Takeaway
Name the relationship explicitly before applying it -- both analogies and classification puzzles reward a stated rule over a guess.
Summary
Analogies require identifying whether a pair's relationship is additive, multiplicative, functional, or categorical, then applying it consistently. Classification asks you to find the shared property of a majority and the one item that breaks it.
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