Can you help me translate the phrase in the title? It refers to finding numbers having a certain characteristic, but I don't know which one: numbers with 2 digits, numbers that are multiples of 2, numbers that have one of the digits 2...

The entire phrase is: "Male in dem Fisch die Fächer farbig aus, in denen Zweierzahlen stehen." It's a math problem for kids. There's a drawing with a fish with little squares showing numbers inside.

  • Could you please quote the entire sentence (before "...in denen"), and the source (book/webpage...)? It is hard otherwise to determine the exact intended meaning, since this is a term of art, not a word from everyday language. Context is king!
    – marquinho
    Feb 10 at 12:26
  • @marquinho Thank you, I've edited the post. Feb 10 at 12:34
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    I would have expected in denen die Zahl zwei steht. It shouldn't be multiples of two, since gerade Zahlen is far better established for that purpose.
    – guidot
    Feb 10 at 12:47
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    This seems to be math terminology that is only used in Grundschule. After googling I think that those are indeed multiples of two.
    – Carsten S
    Feb 10 at 13:58
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    My first guess would have been multiples of 2, as well. But at least occasionally binary numbers are called "Zweierzahlen". See for example "Bei den Binärzahlen (auch „Zweierzahlen“ genannt) ..." here or "Zweierzahlen heißen auch Dualzahlen oder Binärzahlen" here. Your best shot would probably be to look into what's taught around this specific exercise. Feb 10 at 14:05

1 Answer 1


Yep, that's actually terminology used in the Grundschule only.

Zweierzahlen are simply the numbers that are multiples of two - I'm not familiar enough with early school terminology in English to know if there's a special term used in English.

  • Am I correct that the more typical term is "gerade"? Perhaps educators felt that this would be confused with the adverb. It seems to me though that using a word that no one else has heard of would be more confusing than helpful. But are you sure it isn't binary? The results Google pulls up seem to lean that way. Anyway, it sounds suspiciously like "new math". I thought the US already tried that so no one else would have to.
    – RDBury
    Feb 10 at 18:13
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    @RDBury Well, I do remember my kids did the same thing in primary school - They've made it through High School and University, so can't have been that wrong. And they learned in fact about "Zweierzahlen", "Viererzahlen", "Dreierzahlen"... where "gerade" wouldn't have worked.
    – tofro
    Feb 10 at 18:16
  • @RDBury Have a look at the context - Colouring a fish and binary numbers simply don't fit into the same (apparently) primary school context. Where I live, binary numbers are first introduced at grade 7 - pupils are well beyond the point where you tend to motivate them with coloring at that grade.
    – tofro
    Feb 11 at 17:07
  • @RDBury You are right. Zweierzahlen are even numbers, and using another term than gerade Zahlen is motivated by "modern" educational concepts (Zweierreihe, Dreierreihe, ...). But I do not think that using this kind of terminology helps children to get a better understanding of basic mathematical ideas.
    – Paul Frost
    Feb 14 at 20:26

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