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

九寸五分[kusungobu] dagger
弦楽五重奏曲[gengakugojuusoukyoku] string quintet
五つ[itsutsu] five
五つ子[itsutsugo] quintuplets
五悪[goaku] the five sins in Buddhism (murder, theft, adultery, falsehood and drink)

五音々階[goononkai] pentatonic scale
五戒[gokai] the five precepts (prohibitions against killing, theft, sexual misconduct, lying and intemperance)
五官[gokan] the five sense organs
五感[gokan] the five senses

御誕生日おめでとうございます[otanjoubiomedetougozaimasu] Happy Birthday
また明日[mataashita] see you tomorrow
旭日[kyokujitsu] rising sun
旭日昇天[kyokujitsushouten] full of vigor and vitality (like the rising sun) (vigour)
或日[aruhi] one day (e.g. "one day while studying, ..")

一日の長[ichijitsunochou] superiority
一日一日[ichinichiichinichi] gradually
一日一夜[ichinichiichiya] all day and night
一日増しに[ichinichimashini] day by day
一日置き[ichinichioki] every other day

易経[ekikyou] I Ching (Yi Jing) or The Book of Changes - one of the Five Classics
一切経[issaikyou] complete Buddhist scriptures
運動神経[undoushinkei] motor nerves
規模の経済[kibonokeizai] economies of scale
共同経営[kyoudoukeiei] joint management

経つ[tatsu] to pass
経る[heru] to pass
経緯[ikisatsu] details
経営[keiei] management
経営グループ[keieiguruupu] management group