ご多忙中[gotabouchuu] in the midst of your work (often used as a formal phrase in business letters, etc.)
多忙[tabou] busy
忙がしい[sewashii] busy
繁忙[hanbou] pressure of business
忙殺[bousatsu] being extremely busy

忙しげ[sewashige] looking busy
気忙しい[kizewashii] restless
忙中[bouchuu] (in the midst of) busyness
心忙しい[kokorozewashii] restless
仕事で忙しい[shigotodeisogashii] busy with one's work

嘘っ八百[usoppappyaku] full of lies
嘘八百[usohappyaku] full of lies
何百[nanbyaku] hundreds
五十歩百歩[gojuppohyappo] six of one and a half dozen of the other
三百[sanbyaku] 300

三百諸侯[sanbyakushokou] all the daimyos
三百代言[sanbyakudaigen] pettifogging lawyer
数百[suuhyaku] several hundreds
生誕百年[seitanhyakunen] 100th birthday anniversary
二百十日[nihyakutooka] 210th day (from the first day of spring according to the lunar calendar)