一も二も無く[ichimonimonaku] unhesitatingly
一言二言[hitokotofutakoto] a word or two
一石二鳥[issekinichou] killing two birds with one stone
一二に及ばず[ichininioyobazu] right away
一姫二太郎[ichihimenitarou] It's good to have a girl first and then a boy

うり二つ[urifutatsu] as alike as two melons (two peas in a pod)
黄道十二宮[koudoujuunikyuu] twelve signs of the zodiac
二度[futatabi] again
最小二乗法[saishounijouhou] least-squares method
三十二分音符[sanjuunibuonpu] 32nd note

黄道十二宮[koudoujuunikyuu] twelve signs of the zodiac
丸十[marujuu] cross in a circle
五十音[gojuuon] the Japanese syllabary
五十音順[gojuuonjun] the syllabary order
五十三次[gojuusantsugi] the 53 Toukaidou stages

五十年祭[gojuunensai] jubilee
五十歩百歩[gojuppohyappo] six of one and a half dozen of the other
五十路[isoji] age fifty
三十戸[sanjikko] thirty houses
三十三所[sanjuusansho] any of a number of sets of thirty-three holy places enshrining Avalokitesvara (esp. those comprising a popular pilgrimage in the Kinki region)

オブジェクト指向[obujekutoshikou] object-oriented
オブジェクト指向言語[obujekutoshikougengo] object-oriented language
ダイヤの指輪[daiyanoyubiwa] diamond ring
医者の指図[ishanosashizu] doctor's mandate
一指[isshi] finger

一指当たり[ichiyubiatari] span
卸売物価指数[oroshiuribukkashisuu] wholesale price index
眼指[manazashi] (a) look
屈指[kusshi] leading
結婚指輪[kekkonyubiwa] wedding ring

胃腸[ichou] stomach
回腸[kaichou] ileum
結腸[kecchou] colon
鼓腸[kochou] flatulence
十二指腸[juunishichou] duodenum

十二指腸虫[juunishichouchuu] hookworm
大腸[daichou] large intestine
脱腸[dacchou] abdominal hernia
断腸[danchou] heartbreak
断腸の思い[danchounoomoi] heartbroken thoughts