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

１枚[ichimai] one thin flat object
一枚下[ichimaishita] one step lower
一枚貝[ichimaigai] univalve
一枚看板[ichimaikanban] (a) leading player
一枚岩[ichimaiiwa] monolith

一枚上[ichimaiue] one step higher
何枚[nanmai] how many thin flat objects?
３枚[sanmai] three flat objects (e.g. tickets, pieces of cloth, etc.)
三枚目[sanmaime] comedian
紙一枚[kamiichimai] one sheet of paper

御目出度う御座います[omedetougozaimasu] congratulations
駄目になる[dameninaru] to spoil
繋ぎ目[tsunagime] joint
軽目焼[karumeyaki] hard caramelized sugar candy
駄目押し[dameoshi] making doubly sure

一つ目[hitotsume] one-eyed
一合目[ichigoume] the start of a climb up a hill
一丁目[icchoume] Block 1
ひと目[ichimoku] (a) glance
一目惚れ[hitomebore] to be taken with someone at first sight (similar to "love at first sight", but not as strong)