DoubleDutchについて、ここに記述してください。

https://www.merriam-webster.com/dictionary/double%20Dutch

Definition of double Dutch 

1 : unintelligible language
2 : the jumping of two jump ropes rotating in opposite directions simultaneously

https://en.wikipedia.org/wiki/Sum_and_Product_Puzzle

1. Puzzle

X and Y are two different whole numbers greater than 1. Their sum is not greater than 100, and Y is greater than X.

S and P are two mathematicians (and consequently perfect logicians); S knows the sum X + Y and P knows the product X × Y. Both S and P know all the information in this paragraph.

The following conversation occurs: 

    S says "P does not know X and Y."
    P says "Now I know X and Y."
    S says "Now I also know X and Y."

What are X and Y?

2. 日本語

「積と和のパズル」で検索するとヒット。　-- ToshinoriMaeno 2019-06-25 05:13:33 http://kumo.sakura.ne.jp/docm/trump.html

「パズルの国のアリス」でも取り上げられている。 http://www.nikkei-science.com/page/magazine/alice/201405/question.html

論理パズル https://www24.atwiki.jp/524287/pages/15.html

No.4 数当てゲーム

catupper/0.幼女問題　　　 https://gist.github.com/catupper/5678658