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

デフォールト値[defoorutochi] default value
ベクトル値[bekutoruchi] vector value
安値[yasune] low price
闇値[yamine] black-market price
引き値[hikine] reduced price

引け値[hikene] closing quotations
下値[shitane] lowest price
価値[kachi] value
価値観[kachikan] sense of values
価値高い[kachitakai] valuable