一騎当千[ikkitousen] being a match for a thousand
一刻千金[ikkokusenkin] every moment is precious
一字千金[ichijisenkin] word of great value
一千[issen] 1,000
一望千里[ichibousenri] sweeping view of the eye

一瀉千里[isshasenri] one swift effort
引き千切る[hikichigiru] to tear off
何千[nanzen] many thousands
海千山千[umisenyamasen] sly old dog
幾千[ikusen] thousands

まっ四角[masshikaku] square
一天四海[ittenshikai] the world
下四半期[shimoshihanki] last quarter (of the year)
弦楽四重奏曲[gengakushijuusoukyoku] string quartet
再三再四[saisansaishi] repeatedly

三寒四温[sankanshion] alternation of three cold and four warm days
四つ[yottsu] four
四つんばい[yotsunbai] (crawl) on all fours
四つ角[yotsukado] four corners
四つ足[yotsuashi] four-footed (animal)