Similar to 数学上の未解決問題
 - 1/2 − 1/4 + 1/8 − 1/16 + ⋯1/2 − 1/4 + 1/8 − 1/16 + ⋯
 - 1/4 + 1/16 + 1/64 + 1/256 + ⋯1/4 + 1/16 + 1/64 + 1/256 + ⋯
 - 2次過程
 - 2次元Two-dimensional space
 - 2の平方根Square root of 2
 - 2の冪Power of two
- 2の補数Two's complement
- 2部グラフBipartite graph
 - 3次元Three-dimensional space
 - 3値論理Three-valued logic
 - 3人旅人算
 - 3の平方根Square root of 3
- 4次元Four-dimensional space
 - 4つの4Four fours
 - 5項補題Five lemma
 - 5次元Five-dimensional space
 - 5の平方根Square root of 5
 - 6の平方根Square root of 6
 - 6次元Six-dimensional space
 - 7の平方根Square root of 7
 - 8の字結び目Figure-eight knot (mathematics)
 - 9項補題Nine lemma
 - 1/100Hundredth
 - 1/6公式
 - 10の平方根
 - 15・290定理15 and 290 theorems
 - 1-形式One-form (differential geometry)
 - 2-形式Two-form