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

夏至[geshi] summer solstice
夏至線[geshisen] Tropic of Cancer
夏至点[geshiten] summer solstitial point
至って[itatte] very much
至らない[itaranai] imperfect

至る[itaru] to arrive at (e.g. a decision)
至る処[itarutokoro] everywhere
至れりつくせり[itareritsukuseri] very polite
至急[shikyuu] urgent
至急便[shikyuubin] express mail