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)

廿日鼠[hatsukanezumi] house mouse (Mus musculus)

廿日[hatsuka] twentieth (day of the month)

弐拾[nijuu] twenty
弐心[nishin] duplicity

弐つ[futatsu] two (used in old or legal documents)

球拾い[tamahiroi] fetching balls
金拾万円[kinjuumanen] 100,000 Yen
屑拾い[kuzuhiroi] ragpicking
収拾[shuushuu] controlling
拾い集める[hiroiatsumeru] to gather

拾い出す[hiroidasu] to single out
拾い上げる[hiroiageru] to pick up
拾いもの[hiroimono] a find
拾う[hirou] to pick up